CA1219330A - Ear pathology diagnosis apparatus and method - Google Patents
Ear pathology diagnosis apparatus and methodInfo
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- CA1219330A CA1219330A CA000444478A CA444478A CA1219330A CA 1219330 A CA1219330 A CA 1219330A CA 000444478 A CA000444478 A CA 000444478A CA 444478 A CA444478 A CA 444478A CA 1219330 A CA1219330 A CA 1219330A
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Abstract
EAR PATHOLOGY DIAGNOSIS APPARATUS AND METHOD
Abstract of the Disclosure A method and apparatus for diagnosing pathologies of the ear, particularly pathologies such as otitis media, directs into the ear canal a sequence of acoustic waves covering a range of frequencies from a few hundred Hz to several kHz and determines the presence or absence of resonance when the incident and reflected waves are combined. The measurements are made without pressurizing the ear canal and it is not required that the contact between the instrument and the ear be air-tight. Accordingly, essentially no discomforture of the patient results from use of the instrument. The requisite measurements are made quickly (of the order of tens of milliseconds) and thus the distorting effects of patient movement are effectively eliminated. An improved version of the instrument is completely self-contained and hand-held and has the form of a "tee" in which the resonant frequency and amplitude are visually indicated by means of horizontally-and-vertically disposed arrays of light-emitting diodes.
Abstract of the Disclosure A method and apparatus for diagnosing pathologies of the ear, particularly pathologies such as otitis media, directs into the ear canal a sequence of acoustic waves covering a range of frequencies from a few hundred Hz to several kHz and determines the presence or absence of resonance when the incident and reflected waves are combined. The measurements are made without pressurizing the ear canal and it is not required that the contact between the instrument and the ear be air-tight. Accordingly, essentially no discomforture of the patient results from use of the instrument. The requisite measurements are made quickly (of the order of tens of milliseconds) and thus the distorting effects of patient movement are effectively eliminated. An improved version of the instrument is completely self-contained and hand-held and has the form of a "tee" in which the resonant frequency and amplitude are visually indicated by means of horizontally-and-vertically disposed arrays of light-emitting diodes.
Description
33C) D66-OOlA
EAR PATHOL~GY DIAGNOSIS APPARATUS AND METHOD
EAR PATHOL~GY DIAGNOSIS APPARATUS AND METHOD
2 Technical F _ld 3The present invention relates generally to 4 devices and methods for diagnosis of pathological ear condi~ions, and particularly to those devices and 6 methods in which there are determined quantities 7 related to the complex acoustic impedance of 8 components of the ear.
g Background Art 10A wide variety of specific pathologic diseases 11 associated with the human and animal ear have been 12 identified. Among the more frequently identified 13 pathologies are those comprising obstruction of the 14 external canal, agenesis of the pinna, atresia of the external canal, perforation of the tympanic membrane, 16 retraction of the tympanic membrane, otitis in its 17 various forms ~adhesive, purulent and non-purulent), 18 otosclerosis, fixation of the stapes, and 19 cholesteatoma, among others. In children, otitis media is one of the most common childhood pathologies.
21 By itself, it is a significant affliction which can 22 lead to serious long-term hearing and learning 23 disabilities if not promptly diagnosed and treated.
24 Further, it is frequently symptomatic of other pathologies, and thus useful in their diagnosis.
26The diagnosis of otitis media in young children 27 is particularly difficult because of the fear, or even 33;~0 l pain, associated with the commonly available 2 techniques of diagnosis. The usefulness of
g Background Art 10A wide variety of specific pathologic diseases 11 associated with the human and animal ear have been 12 identified. Among the more frequently identified 13 pathologies are those comprising obstruction of the 14 external canal, agenesis of the pinna, atresia of the external canal, perforation of the tympanic membrane, 16 retraction of the tympanic membrane, otitis in its 17 various forms ~adhesive, purulent and non-purulent), 18 otosclerosis, fixation of the stapes, and 19 cholesteatoma, among others. In children, otitis media is one of the most common childhood pathologies.
21 By itself, it is a significant affliction which can 22 lead to serious long-term hearing and learning 23 disabilities if not promptly diagnosed and treated.
24 Further, it is frequently symptomatic of other pathologies, and thus useful in their diagnosis.
26The diagnosis of otitis media in young children 27 is particularly difficult because of the fear, or even 33;~0 l pain, associated with the commonly available 2 techniques of diagnosis. The usefulness of
3 examination by conventional otoscopic techniques is
4 often diminished by the discomfort of the child which leads, at best, to movement by the child which impairs 6 the examination and, at worst, to a refusal to allow 7 the examination to proceed. The problem is especially 8 acute when the examination is to be made in the 9 environment of a mass screening, such as may take place in hospital clinics where large numbers of ll patients must be seen in a comparatively short time.
12 Similar problems are encountered in the useage of 13 other diagnosis techniques, such as tympanometry.
14 Acoustic impedance measurements have also frequently been used to examine various 16 characteristics of the ear in support of medical 17 diagnosis. Prior-art acoustic impedance measurements 18 of human ear structures are usefully summarized in the l9 following patents:
Measurement Frequency Ear Canal 21 Patent Inventor Technique In Hertz Seal Reguired 22 3,294,193 Zwislocki Impedance 220 Yes 23 Bridge 3,757,769 Arguimbau Measure 220 ~ 660 Yes 26 Complex Y
28 4,002,161 Klar Measure 220 Yes 29 Compliance 31 4,009,707 Ward Measure 220 Yes 3~
Compliance 3 4,079,198 Bennett Impedance Variable Yes 4 Bridge See also Pinto and Dallos, "An Acoustic Bridge 6 for Measuring the Static and Dynamic Impedance of the 7 Ear Drum", IEEE Transactions on Bio-Medical 8 Engineerinq~ Volume PME-15, No. 1, January 1968, Pages 9 10-16.
Typically, a probe such as that described in 11 ~nited States Patent 4,057,051 (Kerovac), is inserted 12 into ~he ear canal in such a way that the ear is 13 effectively sealed from the external atmosphere. The 14 probe is usually supplied with a means for varying the pressure within the ear canal above and below ambient lS pressure.
17 While the pressure is being varied, or at 18 selected fixed values of pressure, a continuous wave 19 (CW) sound signal, of constant amplitude, is introduced into the ear canal. The signal from the 21 sound source, and the signal from the probe-mounted 22 transducer, are variously combined to yield a measure 23 of simple compliance (Klar, and Ward), impedance 24 (Zwislocki~ Bennett), or complex admittance (Arguimbau), at the entrance to the ear canal.
26 In most cases ~Arguimbau, Klar, Ward), the 27 measurement of acoustic admittance or compliance is 28 direct, and made at a frequency of 220 or 660 Hz. In 29 other cases (Bennett), impedance measurements are made in a bridge circuit, with an "Artificial Ear" as a 31 reference, over a wider frequency range.
32 Commercially-available forms of the devices 33 described in the above references include the Hetz 34 bridge, the Madsen Z0 70 electroacoustic impedance 1 meter, and the Grason-Stadler model 1720 otoadmittance 2 meter. In each of these devices, the external ear 3 canal is sealed air tight and the pressure in it is 4 varied from +200 mm of water to -400mm while a selec~ed characteristic of the eardrum is measured.
6 In the Metz and Madsen devices, the selected 7 measurement is the impedance (or compliance) of the 8 eardrum at a single pre-selected frequency. In the 9 Grason-Stadler device, the selected characteristic is the conductance ~or susceptance) of the canal at two 11 different frequencies, namely, 220 Hz and 660 Hz.
12 These approaches share many common 13 characteristics: (1) measurements are made with low 14 frequency CW audio signals, (2) an air-tight seal is required as a prerequisite for useful measurement, (3) 16 any probe assembly must be inserted deep into the ear 17 canal, (4) the air pressure in the ear canal must be 18 varied above and below atmospheric for useful 19 measurements, and ~5) no continuous real-time display of diagnostic data is provided, (6) highly trained 21 personnel are frequently required to conduct the test 22 and to interpret the results, (7) the devices are 23 frequently bulky, complex, and expensive, t8) patient 24 cooperation is often a prerequisite to useful results.
Commonly patients subjected to these diagnostic 26 techniques may experience considerable discomfort.
27 This is particularly the case with respect to young 28 children (e.g., from a few months up to ten years old) 29 who are apt to squirm and wiggle and thus make it more difficult to make the measurement and even, in some 31 case, refuse to cooperate at all, particularly where 32 prior experience with such measurements has resulted 33 in significant discomfort.
1215~330 Disclosure of Invention 2 In accordance with the present invention, I
3 provide a simple, yet effective device (hereinafter 4 denominated "reflection analyzer") and method for determining pathologic conditions of the ear. While 6 the device and method of the present invention may 7 advantageously be used for determining a wide range of 8 possible pathologies, they are particularly useful for g diagnosing the presence or absence of otitis media in young children, since the device and method are 11 extremely fast in operation, thereby eliminating 12 artifacts caused by motion of the child during 13 testing; do not require pressurization of the ear 14 canal, thereby eliminating a major source of the pain and fear associated with prior common measurement 16 techniques; and do not require air tight physical 17 contact between the measurement device and the ear of 18 the patient being tested, or deep penetration into the 19 ear canal, thereby further minimizing fear and eliminating pain otherwise associated with testing.
21 The present invention provides a unique method 22 and apparatus that is particularly useful for 23 diagnosis of effusions of the middle ear associated 24 witn otitis media. The method is practiced by determining a quantity related to the complex acoustic 26 impedance of the middle ear, namely, the vector sum of 27 an incident signal impinging on a microphone and 28 thereafter propagating down the ear canal (treated as 29 a lossy transmission line), and the same signal reflected back to the microphone from the ear, 31 particularly from the tympanic membrane (ear drum) and 32 middle ear components.
33 The results of such determination, made, in a 34 preferred embodiment, over a wide band of audio 1 frequencies (typically 1 RH~ to 15 KHz), are examined 2 to determine whether there is present a pathological 3 dip in this vector sum, of a characteristic shape, and 4 typically in a characteristic frequency region having a cen~er lying between approximately 1.5 KHz and 5.5 6 ~Hz, deperding on the age of the patient, the length 7 of the probe, and on the ear pathology involved.
8 The method may be practiced with the apparatus of 9 the present invention, which, in a preferred embodiment, comprises a reflection analyzer including 11 a test head having a sound cavity, a transducer placed 12 so as to create a sound field in the cavity, a hollow 13 probe for conveying sound from the cavity to the 14 vicinity of the ear canal, and for impedance matching to the ear canal, and a microphone suit~bly placed at 16 the junction of the cavity and the probe. The 17 analyzer also has a signal generator connected to the 18 transducer, and appropriate arra~gements for 19 processing the signal from the microphone.
In a prefesred embodiment, the analy~er provides 21 a pulsed or continuous wave signal, that, over a 22 suitable interval of time, varies in frequency and 23 amplitude. With the apparatus so described, the 24 method may be practiced with the ear at atmospheric pressure, and at least partially open to air in the 26 atmosphere, thus making the invention particularly 27 useful in the diagnosis of middle ear disease in young 28 children and infants where insertion of probes and 29 sealing the ear canal is either not desirable or not feasible. Specifically, the requisite measurements 31 may be made with the measuring instrument of the 32 present invention lightly touching the ear being 33 examined but not necessarily forming an air tight seal 34 with the ear. Thus, the pressure of the device 333() 1 against the ear is minimal and one source of possible 2 pain essentially eliminated. Further, the measurement 3 is typically made in a very short period of time, 4 e.g., as little as twenty milliseconds (20 ms) or even less. Thus, the possibility of patient movement 6 during the measurement sufficient to significantly 7 interfere with the measurement is also essentially 8 eliminated. Accordingly, the measurement is extremely 9 fast, relatively accurate, non-invasive, and free of the pain commonly associated with such measurements.
11 Thus, it is of significant utility in all kinds of 12 diagnostic situations with respect to ear pathology, 13 but particularly in those involving mass screening of 14 the ears of young children for common pathologies such as Otitis Media.
16 The utility of the apparatus of the present 17 invention is further enhanced in a second physical 18 embodiment of the analyzer which takes the form of a 19 "tee" held in a hand of the operator. A number of 2U indicating devices, such as light emitting diodes 21 (LED's), are positioned lengthwise along the 22 horizontal arm of the tee, as well as vertically along 23 the vertical leg of the tee, on a face of the device 24 which is turned toward the user. The sound-emitting portion is positioned on the opposite face of the 26 device, toward the patient being examined. The 27 horizontally-oriented diodes indicate the frequency at 28 which the selected indicating phenomenon (here, the 29 dip in the vector sum) occurs, while the vertically oriented diodes indicate the magnitude of the dip in 31 decibels. Thus, the diagnostic data is quickly and 32 conveniently presented to the clinician in a clear and 33 unambiguous form which is particularly useful in mass 34 screening situations.
3~0 1 Accordingly, it is an object of the invention to 2 provide an improved method and device for measuring 3 ear pathologies.
4 Further, it is an object of the invention to provide a method and device for measuring ear 6 pathologies which is particularly convenient to use.
7 Another object of the invention is to provide a 8 device for measuring ear pathologies which performs 9 the measurement rapidly ar.d which quickly displays the result in a form convenient to the user.
11 Yet another object of the invention is to provide 12 a device for measuring ear pathologies that is 13 particularly suited for measuring ear pathologies of 14 young children.
Still a further object of the invention is to 16 provide a device for measuring ear pathologies which 17 is well suited for mass-screening applications.
18 Brief Description of the Drawings 19 Fig. 1 shows a perspective view of a first physical embodiment of a test head in accordance with 21 the present invention;
22 Fig. 2 shows a cross-section of the test head 23 illustrated in Fig. l;
24 Fig. 3 presents a block diagram of an analog apparatus in accordance with the invention which 26 utilizes a continuous sweep system;
27 Fig. 4 presents a graph of measurements of the 28 vector sum in a typical normal ear and the same 29 quantity in an ear having a middle ear effusion;
Fig. 5 presents a block diagram of an apparatus 31 in accordance with the present invention utilizing a 32 train of short audio pulses incremented in successive 33 frequency steps;
121~3~0 1 Fig. 6 shows a block diagram of a digitalized 2 version of an embodiment of the invention utilizing a 3 discrete sweep system;
4 Figs. 7 and 8 are front and rear perspective views, respectively, of a further physical embodiment 6 of a reflection analyzer in accordance with the 7 present invention;
8 Fig. 9 is a vertical sectional view of the 9 analyzer along the lines 9-9 of Fig. 7 and 8.; and 1~ Fig. 10 is a block and line diagram of 11 measurement circuitry for the analyzer of Figs. 7-9.
12 Description of Specific Embodiments 13 Fig. 1 is a perspective view of a test head 34 in 14 accordance with a preferred embodiment of the present invention.
lS The microphone preamplifier 13a, is shown mounted 17 on the rear of the transducer assembly 13. A
18 microphone (shown in later figure) is mounted inside 19 the hollow probe assembly 12. The diameter of the probe assembly is adjusted by changing the probe 21 extension 11. The probe assembly 12 includes funnel-22 shaped section 12 in communication with sound cavity 23 housing 14. The toggle switch 15 on handle 17 24 controls a recorder for capturing the output of the instrument. One of the cables 16 is shielded and 26 carries signals from the probe-mounted preamplifier, 27 while the other cable carries recorder control 28 signals.
29 Fig. 2 shows in cross section a view of the test head in Fig. 1. The test head includes a transducer 31 21 that creates a sound field in sound cavity 23.
32 Sound in the cavity 23 is channeled through probe 25 33 to the vicinity of the ear canal 290. The probe has a ~21~330 1 funnel-shaped section 251 and two-piece linear section 2 252. ~ection 252 is choosen to match the dimensions 3 of the typical healthy ear canal under test. This 4 thereby matches the impedance of the probe tip and the typical ear canal. For children's ears, I have found 6 that generally excellent results are obtained with 7 length A of the linear portion 252 of the probe equal 8 to approximately 1 cm and inner diameter B of the same 9 section in the range of approximately .25 to .75 cm.
Similarly, good results are obtained when length C
11 along the side of portion 251 of the probe is about 5 12 cm and the appoximate outer diameter ~ of the large 13 end of the probe which is in contact with the sound 14 cavity wall, is approximately 7 cm.
Although in some instances it may be desirable to 16 substitute a probe extension with continuously 17 variable inner diameter to match more exactly the 18 input impedance of the ear canal under test, I have 19 not found this to be mandatory for useful results.
Good results have been obtained with a series of three 21 probe extensions to match generally the ear canal 22 impedances of infants children, and adults.
23 The operating principles of the invention are 24 such that the probe extension need not be inserted into the ear canal. In practice there may be a narrow 26 gap 2~ between the test head probe tip 27 and the 27 entrance to the ear canal 290. Control of this gap 28 may be facilitated by a sponge rubber spacer attached 29 at the end of probe tip 27.
The incident sound wave created by transducer 21 31 in the test head emanates from the test head at the 32 tip 27 of the probe 25 and enters the ear canal 290.
33 Thereafter, a portion of the incident wave is 34 reflected by structures of the ear, including the 12~5~330 1 tympanic membrane, stapes, and other components of the 2 middle ear. The amplitude and phase of the reflected 3 sound wave are a function of the test frequency used 4 and the complex acoustic impedance of the ear canal and middle ear. In a healthy ear, one expects some 6 minimal reflection from the tympanic membrane and 7 middle ear. This can be suppressed by suitable 8 selection of the inner probe tip diameter, e.g. by 9 enlarging it to 1.0 cm for children. The complex acoustic impedance of the middle ear, in turn, depends 11 very strongly on the conditions within the middle ear, 12 and in particular on whether there is effusion present 13 within the ~iddle ear.
14 A portion of the reflected wave enters at tip 27 into the hollow probe 252 of the test head. The 16 microphone 24 is located within the test probe 25 at 17 the junction of the straight section 252 and the 18 conical section 251. As a result, the microphone 24 19 measures the net sound pressure at this point; this net sound pressure is the vector sum of the incident 21 and reflected signals. In order to reduce internal 22 sound reflection and resonances within the test head, 23 the sound cavity 23 is filled with loosely packed 24 glass fibers. Good results have been obtained when the transducer 21 is one side of an electrostatic head 26 phone, such as Xoss ESP/10. In this preferred 27 embodiment, the microphone is a condenser microphone.
28 Fig. 3 illustrates in a block diagram an 29 embodiment of the apparatus of the invention utilizing all analog techniques with a continous sweep system.
31 A sweep generator 31 provides a swept frequency output 32 over line 312. Typically, the sweep may be from 1 kHz 33 through about 1~ kHz. A typical period for a full 34 sweep may range from 20 milliseconds to about 10 ~1'333~
1 seconds. These are, however, only typical figures.
2 All that is necessary is that there be a frequency 3 output that covers one or more of the resonant points 4 of the ear canal ~transmission line" as "terminated"
by the middle ear. These points occur regularly at 6 multiples of one quarter wavelength. The following 7 resonant points have been found to be particularly 8 useful for diagnostic purposes: 1/4 wave, 1/2 wave, 9 3/4 wave, and one wavelength. In normal adult ear these wavelengths correspond to frequencies of 11 approximately 3.5, 7, 10.5, and 14 KHz.
12 The sweep signal itself appears as an output over 13 line 311 for use in synchronizing the display device 14 39. The sound pressure from the transducer is kept at a constant level by feedback over line 322 to the 16 attentuator 32. The voltage-controlled attenuator in 17 this embodiment is continously adjustable to a maximum 18 of_20 d8.
19 The output from the microphone 24 shown in Fig. 2 is sent over line 341 from the test head 34 through a 21 preamplifier 35 to a bandpass filter 36. The bandpass 22 filter typically passes signals from approximately 500 23 kHz to 20 kHz. The output of the bandpass filter 36 24 goes into both an RMS to DC converter 371 and a phase ~5 detector 372, so as to provide information as to both 26 amplitude and phase of the signal in the microphone, 27 which, as discussed in connection with Fig. 2, is the 28 vector sum of the incident and reflected signals. The 29 outputs of these devices 371 and 372 are then fed to an appropriate display device. Where the device is an 31 oscilloscope, a high sweep rate, typically 50 Hz, can 32 provide a flicker-free display. When the display 33 device is a chart recorder, the sweep rate is 34 typically 1 second or longer.
Fig. 4 shows a typical graph produced when the ~ embodiment shown in Fig. 3 is used in testing for 3 middle ear effusion and otitis media. Curve 41 is a 4 typical response curve for a nearly normal ear of a five year old child, while curve 42 is a typical curve 6 for this same child with a pronounced middle ear 7 effusion. I haye discovered that the presence of 8 effusion ca~ses a pronounced dip in the magnitude of 9 the vector sum at a frequency associated with quarter wave resonance (about 3.5 kHz in an adult) and have 11 confirmed the theoretical validity of the dip as a 12 diagnostic tool by computer analysis and modeling.
13 Fig. 5 shows another embodiment of the apparatus 14 of the present inventi~n. In this embodiment, a train of pulsed signals is used, each pulse at a different 16 frequency. Components bearing numbers corresponding 17 to those numbers discussed in connection with Fig. 3 18 function in a manner analogously to their 19 correspondingly numbered components in Fig. 3. In the embodiment shown in Fig. 5, however, the signal to the 21 test head 34 originates with the pulse-sweep generator 22 51. The generator provides a series of pulses, each 23 of which had a width of approximately 10 milliseconds, 24 with a pulse repetition rate of approximately 100 Hz.
Each has a different center frequency, the first pulse 26 having a frequency of approximately 1 kHz. Each 27 succeeding pulse has a center frequency approximately 28 120 Hz higher than its predecessor pulse, until the 29 final pulse in a given train of pulses has a frequency of approximately 7 kHz. A complete diagnostic 31 ~easurement can be made with a .5 second long burst of 32 50 pulses.
33 A digital version of the apparatus employing 34 discrete frequency jumps in a CW signal is illustrated 1 in block diagram in Fig. 6. The processing of the 2 signal from the microphone output of the line 341 is 3 similar to the processing shown in connection with 4 Figs. 3 and 5. The principal difference is in the method of generating the signal going to the 6 transducer in the test head 34. The signals are 7 generated in a microprocessor-based computer 611. The 8 computer's input and output are over lines 632 and 621 9 respectively from analog-to-digital converter 63 and ~ digital-to-analog converter 62, respectively.
11 Similarly, the converters 62 and 63 are each preceded 12 ~in the case of A/D converter 63) or followed (in the 13 case of D/A converter 62) by an anti-aliasing bandpass 14 filter 65-64 and buffer amplifiers 67-66. Buffer amplifier 67 receives over line 671 the output from 16 the multiplexer 6~, which in turn receives the 17 information ~rom the RMS-to-DC converter 371 and phase 18 detector 372, which were discussed in connection with 19 ~ig. 3.
In this fashion, the processed microphone output 21 (vector sum signal) passes through multiplexer 69, 22 buffer amplifier 67, anti-aliasing bandpass filter 65, 23 and analog-to-digital converter 63, to the 24 microprocessor 611 so that additional signal processing can be performed to enhance the diagnostic 26 value of the basic vector sum signal.
27 The microprocessor generates the swept signals 28 that go to the transducer over line 681 via power 29 amplifier 68. The signal waveforms are stored in tables in computer memory containing time-sampled 31 wavefGrms, so that the signals are generated 32 digitially for every frequency sweep. Entries in the 33 tables are scanned at user-defined rates, to produce 34 the stepped frequency sweeps. In this fashion, there 1 can be controlled many different parameters, such as 2 starting frequency, stopping frequency, frequency step 3 size, frequency linearity, etc. This same technique 4 provides precise control over the amplitude of the signal at each frequency step, so as to compensate for 6 (for instance) signal channel yain variations between 7 the ou~put of digital-to-analog converter 62 and the 8 transducer in the test probe discussed with reference 9 to Fig. 2. Further, with respect to signal generation, use of the approach shown in Fig. 5 11 permits user control over signal type (e.g., pulse or 12 CW), signal amplitude, and signal phase, whether the 13 signal includes a burst of pulses as the device in 14 connection with Fig. 5 or a continous analog generated sweep, as in Fig. 3. Furthermore, processing of the 16 collected data can also be achieved readily.
17 Quantitative results can be displayed, or the computer 18 can be asked to detect the presence, frequency center 19 line, shape and depth of the characteristic dip described previously, and give a single ngo" - nno go"
21 i.e., effusion - no effusion~ response to the user.
22 Turning now to Figs. 7 through 9, an alternative 23 physical embodiment of the reflection analyzer of ~he 24 present invention is shown in detail. The analyzer of Figs. 7 through 9 is completely self-contained; is 26 small enough to be held in the user's hand, and is 27 thus readily portable; and provides a particularly 28 convenient output display for quickly informing the 29 user-clinician of the condition of the ear being examined. The analyzer of this embodiment comprises a 31 hand-held ca~ing 400 in the form of a "tee" having a 32 horizontal upper arm 402 and a vertically-extending 33 lower arm 404. A probe assembly 406, corresponding to 34 the probe assembly 12 of Figs. 1 and 2, is mounted on 121~3330 1 a front face 408 oE the probe. A back face 410 of the 2 probe (Fig. 8) carries a switch 412, a horizontal row 3 of light-emitting diodes 414 and a ver~ical row of 4 light emitting diodes 416.
S The diodes 414 indicate the frequency at which 6 the resonance dip occurs, while the diodes 416 7 indicate the amplitude of the dip. For purposes of 8 illustration, a sequence of ten diodes has been shown 9 in the horizontal row 414 and, thus, the range of zero to 7500 Hz can be covered by energizing the diodes at 11 frequencies which are spaced 750 Hz apart from each 12 other. ~requencies in between the frequencies 13 precisely corresponding to any pair of diodes may be 14 indicated by energizing two diodes simultaneously and proportionally to the closeness of the corresponding 1~ frequency of the respective diodes so that the 17 amplitude of light emitted by the respective diodes is 18 an indication of how close the resonance (dip) 19 frequency is to the respective diodes. A skilled clinician is rapidly able to interpolate the actual 21 frequency from this information with surprisingly good 22 accuracy.
23 The probe assembly 406 is shown in greater detail 24 in Fig. 9 which is a cross-sectional view along the lines 9-9 of Fig. 7. The assembly comprises a conical 26 shell 420 extending from the front face 408 of the 27 analyzer and terminating in a tip 422 through which 28 the acoustic waves pass into an ear 424 adjacent to 29 which the analyzer is positioned. As was the case with the probe assembly 12 of Fig. 2, the interior of ~1 the shell 420 is hollow and contains a first acoustic 32 transducer in the form of a miniature loudspeaker 426 3~ mounted in a conical shell 428 and surrounded by 34 sound-absorbing material 430 such as an open cell 121~3~0 polyurethane foam. The foam introduces acoustic 2 resistance within the conical shell 420 which serves 3 to minimize undesired acoustic reflections and 4 resonances within the shell; additionally, it broadens the measured resonance.
6 Positioned towards the front of the shell 420, 7 but behind the rear of the tip 422, is a second 8 acoustic transducer 432 comprising a microphone. The 9 microphone 432 is preferably disposed with its input surface oriented in a horizontal plane aligned with 11 the bottom of the tip opening and immediately adjacent 12 the tip opening (as seen in Fig. 9), this point is 13 selected to minimize undesired reflections. The 14 microphone measures the sound pressure level at its sur~ace which, as was the case with the microphone 24 16 of Fig. 2, is the vector sum of the pressure generated 17 by speaker 426 and the pressure generated by the back 18 reflections from ear 424. As was the case with the 19 embodiment of Figs. 1 and 2, and as shown in detail in Fig. 4, the net sound pressure at the microphone 432 21 will exhibit a pronounced dip at around 3500-4000 Hz 22 in the prsence of otitis media as the applied sound 23 wave is swept over a frequenc~ from a low value (e.g., 24 a few hundred hertz) to a higher value (e.g., ~ to 7 kHz). In contrast, a healthy ear will exhibit no such 26 sharp dip and thus a diagnosis of a pathologic 27 condition is readily made.
28 The entire electronics for generating and 29 processing the acoustic signals is contained within the shell 400. In particular, a printed circuit board 31 440 carries the typical components 442 such as 32 capacitors, resistors, integrated circuits, diodes, 33 etc. as well as one or more batteries 444 which 34 provide power for the operation of the unit. Leads 1 446 and 448 connect the speaker q26 and the microphone 2 432, respectively, to the circuit board.
3 ~.s noted previously in connection with the probe 4 assembly 12 of Figures 1 and 2, the analyzer 400 of Fig. 7 through 9 detects resonances occurring at 1/4, 6 1/2, 3/4 and 1 wavelengths, respectively. Consistent 7 with this mode of operation, a physical embodiment of 8 the analy7er of Fig. 7 through 9 has been constructed 9 with a cone length n f" equal to about 7.3 cmm to thereby position the microphone at a mode for unwanted 11 reflections three-quarter wavelength; a tip length "b"
12 equal to 1 cm; a tip inner diameter ~c~ equal to 0.5 13 cm lfor neonates; for children and adults the 14 appropriate diameters are 1 and 2 cm, respectively~.
Control of the position of the microphone 432 with 16 respect to the speaker 426 and the tip 422 in this 17 manner can significantly contribute to the unifo~mity 18 of response across a range of frequencies.
19 The inner diameter "c" of the tip determines the impedance matching between the analyzer and the ear 21 424. Effectively, it acts as an impedance transformer 22 between the two and, by proper proportioning of the 23 inner diameter, allows one to remove the analyzer 400 24 from direct contact with the ear 4~4 and separate them by a small gap 9 which may be 1 millimeter or so.
26 This leads to several significant benefits. To begin 27 with, the fact that the instrument need not have an 2B air-tight seal to the ear significantly reduces the 29 fear of the patient, particularly children, and encourages their cooperation in the measurement. This 31 is in marked contrast to prior instruments which may 32 clamp extensive apparatus around the patient's head 33 and pressurize the ear canal. Further, decoupling the 34 analyzer from the need for exact positioning with ~2~ o 1 respect to the ear allows rapid but accurate analysis 2 of ear pathologies, a characteristic which is 3 particularly important in mass screening situations 4 such as in the clinics of large urban hospitals.
The tip 422 may be proportioned to the ear canal 6 diameters of the population being examined (e.g., 7 neonates, children, adults) or may be selected to be 8 such that it can accomodate measurements on one 9 element of the population (e.g., adults) with a minimum, yet acceptable, sensitivity, and will thus 11 accomodate measurements on the other elements of the 12 population with higher sensitivity. For example, the 13 diameter of the outer ear canal of neonates is of the 14 order of 2.0 mm; that of children is of the order of 4 mm; and that of adults is of the order of 8 mm. By 16 utilizing a tip having compromise inner 100 mm, one 17 provides at least a limited degree of decoupling 18 between the analyzer and the ear with respect to 19 adults; a somewhat greater degree of decoupling with respect children; and the maximum de~ree of decoupling 21 with respect to infants. Thus, the decoupling is the 22 most for those patients who can be expected to be the 23 most cooperative and the least for those who are 24 likely to be the least cooperative, which is precisely what is desired.
26 It should be noted that as the ratio of tip 27 diameter to ear canal diameter increases, the 28 resonance dip becomes more shallow; broadens to a 29 certain extent; and may shift in frequency. Thus, it is desirable to balance the desire for maximum 31 decoupling (which calls for large ratios of tip 32 diameter to ear canal diameter) with the desire for 33 maximum diiferentiation between (which calls for 34 smaller ratios of tip diameter to ear canal diameter).
121~330 My invention allows the designer to establish the 2 desired balance conveniently and inexpensively.
3 Further, by providing the clincian with a variety of 4 tips which can be fitted to the conical shell 406 ~e.g., by snap-fit, threaded fit, or other well known 6 attaching means), the clinician can himself select the 7 tip most suited to the patient being examined. Where 8 a single tip diameter only is to be provided, it is g preferred that a tip diameter of from one to two times the diameter of the typical ear canal to be examined 11 be used to thereby balance analyzer sensitivity in 12 distinguishing healthy ear from diseased ears 13 (smaller ratio indicated) against desired decoupling 14 (larger ratio desired).
Pig. 10 is a simplified block and line diagram of 16 driving and measurement circuitry particularly suited 17 to the analyzer of ~igs. 7-9. Generator 450 generates 18 a rising ramp which drives a voltage controlled 19 oscillator 452 to generate a sinusoidal wave output of continuously increasing frequency. Preferably, the 21 frequency increases from a low frequency (e.g.
22 approximately 150 Hz) to approximately 7 kllz in a time 23 duration of on the order of 70 ms. The output of the 24 oscillator 452 is applied to an amplifier 454 and thence to the speaker 426 in head 406. The acoustic 26 waves generated by the speaker 426 are fed through the 27 probe tip and into the ear 424. The reflected waves 28 return through the tip of the probe 406 and impinge 29 upon the microphone 432, together with the incident wave~ from speaker 426. The output of the microphone 31 is fed to an amplifier 456 and thence to a detector 32 458 which follows and measures their amplitude.
33 A null detector 460 follows the output of 34 amplitude detector 458 and stores the minimum 33;~) 1 amplitude of the particular measurement. The null is 2 determined to be at that frequency at which the 3 amplitude again begins rising (by more than a 4 predetermined thereshold amount) after falling for at least a predetermined amount. The threshold levels 6 are selected to provide acceptable sensitivity while 7 masking noise and other artifacts in a manner known to those skilled in the art. The null detector provides 9 a gating signal 46~ to a gate 464 on detection of a null. Gate 464 couples the instantaneous output of 11 the ramp generator 450, at the time of the gating 12 signal 462, tc frequency hold circuitry ~66 which 13 records the frequency corresponding to the occurrence 14 of a minimum as marked by null detector circuit 460.
An output signal corresponding to the null frequency 16 is applied to the frequency display portion of the 17 analyzer (which includes the frequency display diodes 18 414) via a display driver 468, while an outp~t 19 corresponding to an amplitude of the detected minimum is applied by null detector 460 to the amplitude 21 display portion of the analyzer ~which includes 22 amplitude display diodes 416) via a display driver 23 470. The precise circuitry forming the elements shown ~4 in Fig. 10 forms no part of the present invention and need not be further described in detail. Further, a 26 "pre-listen" control may advantageously be utilized to 27 suppress the measurement during periods of high ~8 ambient environmental noise.
29 It will be understood by those skilled in the art that the resonance condition can also be determined 31 from the large phase shift that accompanies the 32 transition through resonance (dip). Thus, detection 33 of this phase shift offers an important alternative 1 approach to detecting the amplitude of the dip at the 2 various resonant points.
3 Conclusion 4 ~rom the foregoing, it will seen that I have provided a significantly improved device for 6 diagnosing ear pathologies. The analyzer of the 7 present invention is useful for a wide range of ear 8 pathologies, and offers significant advantages with g respect to ease of use, speed of use, and minimal physical contact with the patient, among other 11 advantages. It is sufficiently sensitive as to detect 12 significant ear pathologies, while passing normal or 13 healthy ears. Further, it is largely immune to 14 environmental noise or patient-induced artifact. It is particularly useful in connection with mass 16 screening situations in which large numbers of 17 examinations must be cond~cted in a comparatively 18 short time, and frequently with patients unable or 19 unwilling to provide any significant degree of cooperation. The analyzer is decoupled from air-tight 21 physical contact with the subject being examined and 22 thus the fear and discomfort frequently associated 23 with instrumental examination of the ear are 24 eliminated. Further, the measurement is made over a very short interval of time and thus the chance of 26 patient movement interfering with the test is 27 minimized.
28 While the invention has been described with 29 particular reference to specific embodiments thereof, it will be understood that it may be embodied in a 31 variety of forms diverse from those shown and 32 described without departing from the spirit and scope 33 of the invention as defined by the following claims.
12 Similar problems are encountered in the useage of 13 other diagnosis techniques, such as tympanometry.
14 Acoustic impedance measurements have also frequently been used to examine various 16 characteristics of the ear in support of medical 17 diagnosis. Prior-art acoustic impedance measurements 18 of human ear structures are usefully summarized in the l9 following patents:
Measurement Frequency Ear Canal 21 Patent Inventor Technique In Hertz Seal Reguired 22 3,294,193 Zwislocki Impedance 220 Yes 23 Bridge 3,757,769 Arguimbau Measure 220 ~ 660 Yes 26 Complex Y
28 4,002,161 Klar Measure 220 Yes 29 Compliance 31 4,009,707 Ward Measure 220 Yes 3~
Compliance 3 4,079,198 Bennett Impedance Variable Yes 4 Bridge See also Pinto and Dallos, "An Acoustic Bridge 6 for Measuring the Static and Dynamic Impedance of the 7 Ear Drum", IEEE Transactions on Bio-Medical 8 Engineerinq~ Volume PME-15, No. 1, January 1968, Pages 9 10-16.
Typically, a probe such as that described in 11 ~nited States Patent 4,057,051 (Kerovac), is inserted 12 into ~he ear canal in such a way that the ear is 13 effectively sealed from the external atmosphere. The 14 probe is usually supplied with a means for varying the pressure within the ear canal above and below ambient lS pressure.
17 While the pressure is being varied, or at 18 selected fixed values of pressure, a continuous wave 19 (CW) sound signal, of constant amplitude, is introduced into the ear canal. The signal from the 21 sound source, and the signal from the probe-mounted 22 transducer, are variously combined to yield a measure 23 of simple compliance (Klar, and Ward), impedance 24 (Zwislocki~ Bennett), or complex admittance (Arguimbau), at the entrance to the ear canal.
26 In most cases ~Arguimbau, Klar, Ward), the 27 measurement of acoustic admittance or compliance is 28 direct, and made at a frequency of 220 or 660 Hz. In 29 other cases (Bennett), impedance measurements are made in a bridge circuit, with an "Artificial Ear" as a 31 reference, over a wider frequency range.
32 Commercially-available forms of the devices 33 described in the above references include the Hetz 34 bridge, the Madsen Z0 70 electroacoustic impedance 1 meter, and the Grason-Stadler model 1720 otoadmittance 2 meter. In each of these devices, the external ear 3 canal is sealed air tight and the pressure in it is 4 varied from +200 mm of water to -400mm while a selec~ed characteristic of the eardrum is measured.
6 In the Metz and Madsen devices, the selected 7 measurement is the impedance (or compliance) of the 8 eardrum at a single pre-selected frequency. In the 9 Grason-Stadler device, the selected characteristic is the conductance ~or susceptance) of the canal at two 11 different frequencies, namely, 220 Hz and 660 Hz.
12 These approaches share many common 13 characteristics: (1) measurements are made with low 14 frequency CW audio signals, (2) an air-tight seal is required as a prerequisite for useful measurement, (3) 16 any probe assembly must be inserted deep into the ear 17 canal, (4) the air pressure in the ear canal must be 18 varied above and below atmospheric for useful 19 measurements, and ~5) no continuous real-time display of diagnostic data is provided, (6) highly trained 21 personnel are frequently required to conduct the test 22 and to interpret the results, (7) the devices are 23 frequently bulky, complex, and expensive, t8) patient 24 cooperation is often a prerequisite to useful results.
Commonly patients subjected to these diagnostic 26 techniques may experience considerable discomfort.
27 This is particularly the case with respect to young 28 children (e.g., from a few months up to ten years old) 29 who are apt to squirm and wiggle and thus make it more difficult to make the measurement and even, in some 31 case, refuse to cooperate at all, particularly where 32 prior experience with such measurements has resulted 33 in significant discomfort.
1215~330 Disclosure of Invention 2 In accordance with the present invention, I
3 provide a simple, yet effective device (hereinafter 4 denominated "reflection analyzer") and method for determining pathologic conditions of the ear. While 6 the device and method of the present invention may 7 advantageously be used for determining a wide range of 8 possible pathologies, they are particularly useful for g diagnosing the presence or absence of otitis media in young children, since the device and method are 11 extremely fast in operation, thereby eliminating 12 artifacts caused by motion of the child during 13 testing; do not require pressurization of the ear 14 canal, thereby eliminating a major source of the pain and fear associated with prior common measurement 16 techniques; and do not require air tight physical 17 contact between the measurement device and the ear of 18 the patient being tested, or deep penetration into the 19 ear canal, thereby further minimizing fear and eliminating pain otherwise associated with testing.
21 The present invention provides a unique method 22 and apparatus that is particularly useful for 23 diagnosis of effusions of the middle ear associated 24 witn otitis media. The method is practiced by determining a quantity related to the complex acoustic 26 impedance of the middle ear, namely, the vector sum of 27 an incident signal impinging on a microphone and 28 thereafter propagating down the ear canal (treated as 29 a lossy transmission line), and the same signal reflected back to the microphone from the ear, 31 particularly from the tympanic membrane (ear drum) and 32 middle ear components.
33 The results of such determination, made, in a 34 preferred embodiment, over a wide band of audio 1 frequencies (typically 1 RH~ to 15 KHz), are examined 2 to determine whether there is present a pathological 3 dip in this vector sum, of a characteristic shape, and 4 typically in a characteristic frequency region having a cen~er lying between approximately 1.5 KHz and 5.5 6 ~Hz, deperding on the age of the patient, the length 7 of the probe, and on the ear pathology involved.
8 The method may be practiced with the apparatus of 9 the present invention, which, in a preferred embodiment, comprises a reflection analyzer including 11 a test head having a sound cavity, a transducer placed 12 so as to create a sound field in the cavity, a hollow 13 probe for conveying sound from the cavity to the 14 vicinity of the ear canal, and for impedance matching to the ear canal, and a microphone suit~bly placed at 16 the junction of the cavity and the probe. The 17 analyzer also has a signal generator connected to the 18 transducer, and appropriate arra~gements for 19 processing the signal from the microphone.
In a prefesred embodiment, the analy~er provides 21 a pulsed or continuous wave signal, that, over a 22 suitable interval of time, varies in frequency and 23 amplitude. With the apparatus so described, the 24 method may be practiced with the ear at atmospheric pressure, and at least partially open to air in the 26 atmosphere, thus making the invention particularly 27 useful in the diagnosis of middle ear disease in young 28 children and infants where insertion of probes and 29 sealing the ear canal is either not desirable or not feasible. Specifically, the requisite measurements 31 may be made with the measuring instrument of the 32 present invention lightly touching the ear being 33 examined but not necessarily forming an air tight seal 34 with the ear. Thus, the pressure of the device 333() 1 against the ear is minimal and one source of possible 2 pain essentially eliminated. Further, the measurement 3 is typically made in a very short period of time, 4 e.g., as little as twenty milliseconds (20 ms) or even less. Thus, the possibility of patient movement 6 during the measurement sufficient to significantly 7 interfere with the measurement is also essentially 8 eliminated. Accordingly, the measurement is extremely 9 fast, relatively accurate, non-invasive, and free of the pain commonly associated with such measurements.
11 Thus, it is of significant utility in all kinds of 12 diagnostic situations with respect to ear pathology, 13 but particularly in those involving mass screening of 14 the ears of young children for common pathologies such as Otitis Media.
16 The utility of the apparatus of the present 17 invention is further enhanced in a second physical 18 embodiment of the analyzer which takes the form of a 19 "tee" held in a hand of the operator. A number of 2U indicating devices, such as light emitting diodes 21 (LED's), are positioned lengthwise along the 22 horizontal arm of the tee, as well as vertically along 23 the vertical leg of the tee, on a face of the device 24 which is turned toward the user. The sound-emitting portion is positioned on the opposite face of the 26 device, toward the patient being examined. The 27 horizontally-oriented diodes indicate the frequency at 28 which the selected indicating phenomenon (here, the 29 dip in the vector sum) occurs, while the vertically oriented diodes indicate the magnitude of the dip in 31 decibels. Thus, the diagnostic data is quickly and 32 conveniently presented to the clinician in a clear and 33 unambiguous form which is particularly useful in mass 34 screening situations.
3~0 1 Accordingly, it is an object of the invention to 2 provide an improved method and device for measuring 3 ear pathologies.
4 Further, it is an object of the invention to provide a method and device for measuring ear 6 pathologies which is particularly convenient to use.
7 Another object of the invention is to provide a 8 device for measuring ear pathologies which performs 9 the measurement rapidly ar.d which quickly displays the result in a form convenient to the user.
11 Yet another object of the invention is to provide 12 a device for measuring ear pathologies that is 13 particularly suited for measuring ear pathologies of 14 young children.
Still a further object of the invention is to 16 provide a device for measuring ear pathologies which 17 is well suited for mass-screening applications.
18 Brief Description of the Drawings 19 Fig. 1 shows a perspective view of a first physical embodiment of a test head in accordance with 21 the present invention;
22 Fig. 2 shows a cross-section of the test head 23 illustrated in Fig. l;
24 Fig. 3 presents a block diagram of an analog apparatus in accordance with the invention which 26 utilizes a continuous sweep system;
27 Fig. 4 presents a graph of measurements of the 28 vector sum in a typical normal ear and the same 29 quantity in an ear having a middle ear effusion;
Fig. 5 presents a block diagram of an apparatus 31 in accordance with the present invention utilizing a 32 train of short audio pulses incremented in successive 33 frequency steps;
121~3~0 1 Fig. 6 shows a block diagram of a digitalized 2 version of an embodiment of the invention utilizing a 3 discrete sweep system;
4 Figs. 7 and 8 are front and rear perspective views, respectively, of a further physical embodiment 6 of a reflection analyzer in accordance with the 7 present invention;
8 Fig. 9 is a vertical sectional view of the 9 analyzer along the lines 9-9 of Fig. 7 and 8.; and 1~ Fig. 10 is a block and line diagram of 11 measurement circuitry for the analyzer of Figs. 7-9.
12 Description of Specific Embodiments 13 Fig. 1 is a perspective view of a test head 34 in 14 accordance with a preferred embodiment of the present invention.
lS The microphone preamplifier 13a, is shown mounted 17 on the rear of the transducer assembly 13. A
18 microphone (shown in later figure) is mounted inside 19 the hollow probe assembly 12. The diameter of the probe assembly is adjusted by changing the probe 21 extension 11. The probe assembly 12 includes funnel-22 shaped section 12 in communication with sound cavity 23 housing 14. The toggle switch 15 on handle 17 24 controls a recorder for capturing the output of the instrument. One of the cables 16 is shielded and 26 carries signals from the probe-mounted preamplifier, 27 while the other cable carries recorder control 28 signals.
29 Fig. 2 shows in cross section a view of the test head in Fig. 1. The test head includes a transducer 31 21 that creates a sound field in sound cavity 23.
32 Sound in the cavity 23 is channeled through probe 25 33 to the vicinity of the ear canal 290. The probe has a ~21~330 1 funnel-shaped section 251 and two-piece linear section 2 252. ~ection 252 is choosen to match the dimensions 3 of the typical healthy ear canal under test. This 4 thereby matches the impedance of the probe tip and the typical ear canal. For children's ears, I have found 6 that generally excellent results are obtained with 7 length A of the linear portion 252 of the probe equal 8 to approximately 1 cm and inner diameter B of the same 9 section in the range of approximately .25 to .75 cm.
Similarly, good results are obtained when length C
11 along the side of portion 251 of the probe is about 5 12 cm and the appoximate outer diameter ~ of the large 13 end of the probe which is in contact with the sound 14 cavity wall, is approximately 7 cm.
Although in some instances it may be desirable to 16 substitute a probe extension with continuously 17 variable inner diameter to match more exactly the 18 input impedance of the ear canal under test, I have 19 not found this to be mandatory for useful results.
Good results have been obtained with a series of three 21 probe extensions to match generally the ear canal 22 impedances of infants children, and adults.
23 The operating principles of the invention are 24 such that the probe extension need not be inserted into the ear canal. In practice there may be a narrow 26 gap 2~ between the test head probe tip 27 and the 27 entrance to the ear canal 290. Control of this gap 28 may be facilitated by a sponge rubber spacer attached 29 at the end of probe tip 27.
The incident sound wave created by transducer 21 31 in the test head emanates from the test head at the 32 tip 27 of the probe 25 and enters the ear canal 290.
33 Thereafter, a portion of the incident wave is 34 reflected by structures of the ear, including the 12~5~330 1 tympanic membrane, stapes, and other components of the 2 middle ear. The amplitude and phase of the reflected 3 sound wave are a function of the test frequency used 4 and the complex acoustic impedance of the ear canal and middle ear. In a healthy ear, one expects some 6 minimal reflection from the tympanic membrane and 7 middle ear. This can be suppressed by suitable 8 selection of the inner probe tip diameter, e.g. by 9 enlarging it to 1.0 cm for children. The complex acoustic impedance of the middle ear, in turn, depends 11 very strongly on the conditions within the middle ear, 12 and in particular on whether there is effusion present 13 within the ~iddle ear.
14 A portion of the reflected wave enters at tip 27 into the hollow probe 252 of the test head. The 16 microphone 24 is located within the test probe 25 at 17 the junction of the straight section 252 and the 18 conical section 251. As a result, the microphone 24 19 measures the net sound pressure at this point; this net sound pressure is the vector sum of the incident 21 and reflected signals. In order to reduce internal 22 sound reflection and resonances within the test head, 23 the sound cavity 23 is filled with loosely packed 24 glass fibers. Good results have been obtained when the transducer 21 is one side of an electrostatic head 26 phone, such as Xoss ESP/10. In this preferred 27 embodiment, the microphone is a condenser microphone.
28 Fig. 3 illustrates in a block diagram an 29 embodiment of the apparatus of the invention utilizing all analog techniques with a continous sweep system.
31 A sweep generator 31 provides a swept frequency output 32 over line 312. Typically, the sweep may be from 1 kHz 33 through about 1~ kHz. A typical period for a full 34 sweep may range from 20 milliseconds to about 10 ~1'333~
1 seconds. These are, however, only typical figures.
2 All that is necessary is that there be a frequency 3 output that covers one or more of the resonant points 4 of the ear canal ~transmission line" as "terminated"
by the middle ear. These points occur regularly at 6 multiples of one quarter wavelength. The following 7 resonant points have been found to be particularly 8 useful for diagnostic purposes: 1/4 wave, 1/2 wave, 9 3/4 wave, and one wavelength. In normal adult ear these wavelengths correspond to frequencies of 11 approximately 3.5, 7, 10.5, and 14 KHz.
12 The sweep signal itself appears as an output over 13 line 311 for use in synchronizing the display device 14 39. The sound pressure from the transducer is kept at a constant level by feedback over line 322 to the 16 attentuator 32. The voltage-controlled attenuator in 17 this embodiment is continously adjustable to a maximum 18 of_20 d8.
19 The output from the microphone 24 shown in Fig. 2 is sent over line 341 from the test head 34 through a 21 preamplifier 35 to a bandpass filter 36. The bandpass 22 filter typically passes signals from approximately 500 23 kHz to 20 kHz. The output of the bandpass filter 36 24 goes into both an RMS to DC converter 371 and a phase ~5 detector 372, so as to provide information as to both 26 amplitude and phase of the signal in the microphone, 27 which, as discussed in connection with Fig. 2, is the 28 vector sum of the incident and reflected signals. The 29 outputs of these devices 371 and 372 are then fed to an appropriate display device. Where the device is an 31 oscilloscope, a high sweep rate, typically 50 Hz, can 32 provide a flicker-free display. When the display 33 device is a chart recorder, the sweep rate is 34 typically 1 second or longer.
Fig. 4 shows a typical graph produced when the ~ embodiment shown in Fig. 3 is used in testing for 3 middle ear effusion and otitis media. Curve 41 is a 4 typical response curve for a nearly normal ear of a five year old child, while curve 42 is a typical curve 6 for this same child with a pronounced middle ear 7 effusion. I haye discovered that the presence of 8 effusion ca~ses a pronounced dip in the magnitude of 9 the vector sum at a frequency associated with quarter wave resonance (about 3.5 kHz in an adult) and have 11 confirmed the theoretical validity of the dip as a 12 diagnostic tool by computer analysis and modeling.
13 Fig. 5 shows another embodiment of the apparatus 14 of the present inventi~n. In this embodiment, a train of pulsed signals is used, each pulse at a different 16 frequency. Components bearing numbers corresponding 17 to those numbers discussed in connection with Fig. 3 18 function in a manner analogously to their 19 correspondingly numbered components in Fig. 3. In the embodiment shown in Fig. 5, however, the signal to the 21 test head 34 originates with the pulse-sweep generator 22 51. The generator provides a series of pulses, each 23 of which had a width of approximately 10 milliseconds, 24 with a pulse repetition rate of approximately 100 Hz.
Each has a different center frequency, the first pulse 26 having a frequency of approximately 1 kHz. Each 27 succeeding pulse has a center frequency approximately 28 120 Hz higher than its predecessor pulse, until the 29 final pulse in a given train of pulses has a frequency of approximately 7 kHz. A complete diagnostic 31 ~easurement can be made with a .5 second long burst of 32 50 pulses.
33 A digital version of the apparatus employing 34 discrete frequency jumps in a CW signal is illustrated 1 in block diagram in Fig. 6. The processing of the 2 signal from the microphone output of the line 341 is 3 similar to the processing shown in connection with 4 Figs. 3 and 5. The principal difference is in the method of generating the signal going to the 6 transducer in the test head 34. The signals are 7 generated in a microprocessor-based computer 611. The 8 computer's input and output are over lines 632 and 621 9 respectively from analog-to-digital converter 63 and ~ digital-to-analog converter 62, respectively.
11 Similarly, the converters 62 and 63 are each preceded 12 ~in the case of A/D converter 63) or followed (in the 13 case of D/A converter 62) by an anti-aliasing bandpass 14 filter 65-64 and buffer amplifiers 67-66. Buffer amplifier 67 receives over line 671 the output from 16 the multiplexer 6~, which in turn receives the 17 information ~rom the RMS-to-DC converter 371 and phase 18 detector 372, which were discussed in connection with 19 ~ig. 3.
In this fashion, the processed microphone output 21 (vector sum signal) passes through multiplexer 69, 22 buffer amplifier 67, anti-aliasing bandpass filter 65, 23 and analog-to-digital converter 63, to the 24 microprocessor 611 so that additional signal processing can be performed to enhance the diagnostic 26 value of the basic vector sum signal.
27 The microprocessor generates the swept signals 28 that go to the transducer over line 681 via power 29 amplifier 68. The signal waveforms are stored in tables in computer memory containing time-sampled 31 wavefGrms, so that the signals are generated 32 digitially for every frequency sweep. Entries in the 33 tables are scanned at user-defined rates, to produce 34 the stepped frequency sweeps. In this fashion, there 1 can be controlled many different parameters, such as 2 starting frequency, stopping frequency, frequency step 3 size, frequency linearity, etc. This same technique 4 provides precise control over the amplitude of the signal at each frequency step, so as to compensate for 6 (for instance) signal channel yain variations between 7 the ou~put of digital-to-analog converter 62 and the 8 transducer in the test probe discussed with reference 9 to Fig. 2. Further, with respect to signal generation, use of the approach shown in Fig. 5 11 permits user control over signal type (e.g., pulse or 12 CW), signal amplitude, and signal phase, whether the 13 signal includes a burst of pulses as the device in 14 connection with Fig. 5 or a continous analog generated sweep, as in Fig. 3. Furthermore, processing of the 16 collected data can also be achieved readily.
17 Quantitative results can be displayed, or the computer 18 can be asked to detect the presence, frequency center 19 line, shape and depth of the characteristic dip described previously, and give a single ngo" - nno go"
21 i.e., effusion - no effusion~ response to the user.
22 Turning now to Figs. 7 through 9, an alternative 23 physical embodiment of the reflection analyzer of ~he 24 present invention is shown in detail. The analyzer of Figs. 7 through 9 is completely self-contained; is 26 small enough to be held in the user's hand, and is 27 thus readily portable; and provides a particularly 28 convenient output display for quickly informing the 29 user-clinician of the condition of the ear being examined. The analyzer of this embodiment comprises a 31 hand-held ca~ing 400 in the form of a "tee" having a 32 horizontal upper arm 402 and a vertically-extending 33 lower arm 404. A probe assembly 406, corresponding to 34 the probe assembly 12 of Figs. 1 and 2, is mounted on 121~3330 1 a front face 408 oE the probe. A back face 410 of the 2 probe (Fig. 8) carries a switch 412, a horizontal row 3 of light-emitting diodes 414 and a ver~ical row of 4 light emitting diodes 416.
S The diodes 414 indicate the frequency at which 6 the resonance dip occurs, while the diodes 416 7 indicate the amplitude of the dip. For purposes of 8 illustration, a sequence of ten diodes has been shown 9 in the horizontal row 414 and, thus, the range of zero to 7500 Hz can be covered by energizing the diodes at 11 frequencies which are spaced 750 Hz apart from each 12 other. ~requencies in between the frequencies 13 precisely corresponding to any pair of diodes may be 14 indicated by energizing two diodes simultaneously and proportionally to the closeness of the corresponding 1~ frequency of the respective diodes so that the 17 amplitude of light emitted by the respective diodes is 18 an indication of how close the resonance (dip) 19 frequency is to the respective diodes. A skilled clinician is rapidly able to interpolate the actual 21 frequency from this information with surprisingly good 22 accuracy.
23 The probe assembly 406 is shown in greater detail 24 in Fig. 9 which is a cross-sectional view along the lines 9-9 of Fig. 7. The assembly comprises a conical 26 shell 420 extending from the front face 408 of the 27 analyzer and terminating in a tip 422 through which 28 the acoustic waves pass into an ear 424 adjacent to 29 which the analyzer is positioned. As was the case with the probe assembly 12 of Fig. 2, the interior of ~1 the shell 420 is hollow and contains a first acoustic 32 transducer in the form of a miniature loudspeaker 426 3~ mounted in a conical shell 428 and surrounded by 34 sound-absorbing material 430 such as an open cell 121~3~0 polyurethane foam. The foam introduces acoustic 2 resistance within the conical shell 420 which serves 3 to minimize undesired acoustic reflections and 4 resonances within the shell; additionally, it broadens the measured resonance.
6 Positioned towards the front of the shell 420, 7 but behind the rear of the tip 422, is a second 8 acoustic transducer 432 comprising a microphone. The 9 microphone 432 is preferably disposed with its input surface oriented in a horizontal plane aligned with 11 the bottom of the tip opening and immediately adjacent 12 the tip opening (as seen in Fig. 9), this point is 13 selected to minimize undesired reflections. The 14 microphone measures the sound pressure level at its sur~ace which, as was the case with the microphone 24 16 of Fig. 2, is the vector sum of the pressure generated 17 by speaker 426 and the pressure generated by the back 18 reflections from ear 424. As was the case with the 19 embodiment of Figs. 1 and 2, and as shown in detail in Fig. 4, the net sound pressure at the microphone 432 21 will exhibit a pronounced dip at around 3500-4000 Hz 22 in the prsence of otitis media as the applied sound 23 wave is swept over a frequenc~ from a low value (e.g., 24 a few hundred hertz) to a higher value (e.g., ~ to 7 kHz). In contrast, a healthy ear will exhibit no such 26 sharp dip and thus a diagnosis of a pathologic 27 condition is readily made.
28 The entire electronics for generating and 29 processing the acoustic signals is contained within the shell 400. In particular, a printed circuit board 31 440 carries the typical components 442 such as 32 capacitors, resistors, integrated circuits, diodes, 33 etc. as well as one or more batteries 444 which 34 provide power for the operation of the unit. Leads 1 446 and 448 connect the speaker q26 and the microphone 2 432, respectively, to the circuit board.
3 ~.s noted previously in connection with the probe 4 assembly 12 of Figures 1 and 2, the analyzer 400 of Fig. 7 through 9 detects resonances occurring at 1/4, 6 1/2, 3/4 and 1 wavelengths, respectively. Consistent 7 with this mode of operation, a physical embodiment of 8 the analy7er of Fig. 7 through 9 has been constructed 9 with a cone length n f" equal to about 7.3 cmm to thereby position the microphone at a mode for unwanted 11 reflections three-quarter wavelength; a tip length "b"
12 equal to 1 cm; a tip inner diameter ~c~ equal to 0.5 13 cm lfor neonates; for children and adults the 14 appropriate diameters are 1 and 2 cm, respectively~.
Control of the position of the microphone 432 with 16 respect to the speaker 426 and the tip 422 in this 17 manner can significantly contribute to the unifo~mity 18 of response across a range of frequencies.
19 The inner diameter "c" of the tip determines the impedance matching between the analyzer and the ear 21 424. Effectively, it acts as an impedance transformer 22 between the two and, by proper proportioning of the 23 inner diameter, allows one to remove the analyzer 400 24 from direct contact with the ear 4~4 and separate them by a small gap 9 which may be 1 millimeter or so.
26 This leads to several significant benefits. To begin 27 with, the fact that the instrument need not have an 2B air-tight seal to the ear significantly reduces the 29 fear of the patient, particularly children, and encourages their cooperation in the measurement. This 31 is in marked contrast to prior instruments which may 32 clamp extensive apparatus around the patient's head 33 and pressurize the ear canal. Further, decoupling the 34 analyzer from the need for exact positioning with ~2~ o 1 respect to the ear allows rapid but accurate analysis 2 of ear pathologies, a characteristic which is 3 particularly important in mass screening situations 4 such as in the clinics of large urban hospitals.
The tip 422 may be proportioned to the ear canal 6 diameters of the population being examined (e.g., 7 neonates, children, adults) or may be selected to be 8 such that it can accomodate measurements on one 9 element of the population (e.g., adults) with a minimum, yet acceptable, sensitivity, and will thus 11 accomodate measurements on the other elements of the 12 population with higher sensitivity. For example, the 13 diameter of the outer ear canal of neonates is of the 14 order of 2.0 mm; that of children is of the order of 4 mm; and that of adults is of the order of 8 mm. By 16 utilizing a tip having compromise inner 100 mm, one 17 provides at least a limited degree of decoupling 18 between the analyzer and the ear with respect to 19 adults; a somewhat greater degree of decoupling with respect children; and the maximum de~ree of decoupling 21 with respect to infants. Thus, the decoupling is the 22 most for those patients who can be expected to be the 23 most cooperative and the least for those who are 24 likely to be the least cooperative, which is precisely what is desired.
26 It should be noted that as the ratio of tip 27 diameter to ear canal diameter increases, the 28 resonance dip becomes more shallow; broadens to a 29 certain extent; and may shift in frequency. Thus, it is desirable to balance the desire for maximum 31 decoupling (which calls for large ratios of tip 32 diameter to ear canal diameter) with the desire for 33 maximum diiferentiation between (which calls for 34 smaller ratios of tip diameter to ear canal diameter).
121~330 My invention allows the designer to establish the 2 desired balance conveniently and inexpensively.
3 Further, by providing the clincian with a variety of 4 tips which can be fitted to the conical shell 406 ~e.g., by snap-fit, threaded fit, or other well known 6 attaching means), the clinician can himself select the 7 tip most suited to the patient being examined. Where 8 a single tip diameter only is to be provided, it is g preferred that a tip diameter of from one to two times the diameter of the typical ear canal to be examined 11 be used to thereby balance analyzer sensitivity in 12 distinguishing healthy ear from diseased ears 13 (smaller ratio indicated) against desired decoupling 14 (larger ratio desired).
Pig. 10 is a simplified block and line diagram of 16 driving and measurement circuitry particularly suited 17 to the analyzer of ~igs. 7-9. Generator 450 generates 18 a rising ramp which drives a voltage controlled 19 oscillator 452 to generate a sinusoidal wave output of continuously increasing frequency. Preferably, the 21 frequency increases from a low frequency (e.g.
22 approximately 150 Hz) to approximately 7 kllz in a time 23 duration of on the order of 70 ms. The output of the 24 oscillator 452 is applied to an amplifier 454 and thence to the speaker 426 in head 406. The acoustic 26 waves generated by the speaker 426 are fed through the 27 probe tip and into the ear 424. The reflected waves 28 return through the tip of the probe 406 and impinge 29 upon the microphone 432, together with the incident wave~ from speaker 426. The output of the microphone 31 is fed to an amplifier 456 and thence to a detector 32 458 which follows and measures their amplitude.
33 A null detector 460 follows the output of 34 amplitude detector 458 and stores the minimum 33;~) 1 amplitude of the particular measurement. The null is 2 determined to be at that frequency at which the 3 amplitude again begins rising (by more than a 4 predetermined thereshold amount) after falling for at least a predetermined amount. The threshold levels 6 are selected to provide acceptable sensitivity while 7 masking noise and other artifacts in a manner known to those skilled in the art. The null detector provides 9 a gating signal 46~ to a gate 464 on detection of a null. Gate 464 couples the instantaneous output of 11 the ramp generator 450, at the time of the gating 12 signal 462, tc frequency hold circuitry ~66 which 13 records the frequency corresponding to the occurrence 14 of a minimum as marked by null detector circuit 460.
An output signal corresponding to the null frequency 16 is applied to the frequency display portion of the 17 analyzer (which includes the frequency display diodes 18 414) via a display driver 468, while an outp~t 19 corresponding to an amplitude of the detected minimum is applied by null detector 460 to the amplitude 21 display portion of the analyzer ~which includes 22 amplitude display diodes 416) via a display driver 23 470. The precise circuitry forming the elements shown ~4 in Fig. 10 forms no part of the present invention and need not be further described in detail. Further, a 26 "pre-listen" control may advantageously be utilized to 27 suppress the measurement during periods of high ~8 ambient environmental noise.
29 It will be understood by those skilled in the art that the resonance condition can also be determined 31 from the large phase shift that accompanies the 32 transition through resonance (dip). Thus, detection 33 of this phase shift offers an important alternative 1 approach to detecting the amplitude of the dip at the 2 various resonant points.
3 Conclusion 4 ~rom the foregoing, it will seen that I have provided a significantly improved device for 6 diagnosing ear pathologies. The analyzer of the 7 present invention is useful for a wide range of ear 8 pathologies, and offers significant advantages with g respect to ease of use, speed of use, and minimal physical contact with the patient, among other 11 advantages. It is sufficiently sensitive as to detect 12 significant ear pathologies, while passing normal or 13 healthy ears. Further, it is largely immune to 14 environmental noise or patient-induced artifact. It is particularly useful in connection with mass 16 screening situations in which large numbers of 17 examinations must be cond~cted in a comparatively 18 short time, and frequently with patients unable or 19 unwilling to provide any significant degree of cooperation. The analyzer is decoupled from air-tight 21 physical contact with the subject being examined and 22 thus the fear and discomfort frequently associated 23 with instrumental examination of the ear are 24 eliminated. Further, the measurement is made over a very short interval of time and thus the chance of 26 patient movement interfering with the test is 27 minimized.
28 While the invention has been described with 29 particular reference to specific embodiments thereof, it will be understood that it may be embodied in a 31 variety of forms diverse from those shown and 32 described without departing from the spirit and scope 33 of the invention as defined by the following claims.
Claims (23)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for diagnosis of pathological ear conditions, such method comprising: (a) applying to the ear canal, which is maintained at atmospheric pressure and at least partially open to air in the atmosphere, an acoustic signal that includes at least one frequency in excess of approximately 1 kHz; (b) measuring the vector sum of the acoustic signal incident on the ear canal and the acoustic signal reflected back from the ear through the ear canal, the vector sum representing a quantity related to the complex acoustic impedance of the ear; and (c) comparing the results obtained in step (b) with the expected results for a healthy ear.
2. A method according to claim 1, wherein steps (a) and (b) include utilizing an apparatus including (i) a test head, having a sound cavity, a transducer, placed so as to create, when energized, a sound field in the sound cavity, a hollow probe, having a large end in communication with the sound cavity and a small end for placement at the entrance of the ear under test, such small end having a cross-sectional area chosen to match generally the dimensions of the ear canal, and a microphone, placed within the test head, said microphone generating a test signal comprising said quantity when said transducer is energized, (ii) generator means, for generating an electrical signal hav-ing components over a suitable frequency range, such means con-nected to the transducer; and (iii) processor means, for proces-sing the signal from the microphone.
3. A method according to claim 2, wherein the generator means includes means for generating a waveform, such as an im-pulse, that simultaneously includes components over a suitable frequency range.
4. A method according to claim 2, wherein the generator means includes means for generating a signal that, over a suit-able interval of time, varies in frequency.
5. A method according to claim 4, wherein the means for generating a signal provides a signal that sweeps smoothly over a suitable frequency range.
6. A method according to claim 4, wherein the means for generating a signal provides a signal that varies in frequency in discrete programmed frequency intervals.
7. A method according to claim 2, wherein step (c) includes the step of determining whether the results obtained in step (b) show a pathological dip in the quantity in a characteristic fre-quency region having a center lying between approximately 1 kHz and 15 kHz.
8. A method according to claim 7, wherein step (c) includes the step of determining whether the results obtained in step (b) show a pathological dip in the quantity in a characteristic fre-quency region having a center lying between approximately 1.5 and 5.5 kHz.
9. A method according to claim 1, wherein step (c) includes the step of determining whether the results obtained in step (b) show a pathological dip in the quantity in a characteristic fre-quency region having a center lying between approximately 1.5 and 5.5 kHz.
10. An apparatus for use in diagnosing pathological ear conditions, such apparatus comprising: a transducer having a tip positionable proximate to the ear canal with the ear at atmos-pheric pressure and at least partially open to air in the atmos-phere, said transducer creating an acoustic signal in said canal;
a microphone proximate to the ear for converting an acoustic sig-nal to an electrical signal; generator means, for generating an electrical signal having components over a suitable frequency range, such means connected to the transducer; and processing means, connected to the microphone, for processing the electrical signal from the microphone to yield a quantity related to the complex acoustic impedance of the ear, including means for in-dicating whether the quantity related to the complex acoustic impedance of the ear has a pathological dip in a characteristic frequency region having a center lying between approximately 1.5 kHz and 5.5 kHz.
a microphone proximate to the ear for converting an acoustic sig-nal to an electrical signal; generator means, for generating an electrical signal having components over a suitable frequency range, such means connected to the transducer; and processing means, connected to the microphone, for processing the electrical signal from the microphone to yield a quantity related to the complex acoustic impedance of the ear, including means for in-dicating whether the quantity related to the complex acoustic impedance of the ear has a pathological dip in a characteristic frequency region having a center lying between approximately 1.5 kHz and 5.5 kHz.
11. An apparatus according to claim 10, in which said tip comprises (i) a hollow probe and (ii) a sound cavity, such probe having a large end in communication with the sound cavity and a small end for placement at the entrance of the ear under test, such small end having a diameter chosen to match generally the diameter of the ear canal.
12. An apparatus according to claim 11, wherein the gener-ator means includes means for generating a waveform, such as an impulse, that simultaneously includes components over a suitable frequency range.
13. An apparatus according to claim 11, wherein the generator means includes means for generating a signal that, over a suitable interval of time, varies in frequency.
14. An apparatus according to claim 13, wherein the means for generating a signal provides a signal that sweeps smoothly over a suitable frequency range.
15. A test head for use in diagnosing pathological ear con-ditions, such test head comprising: a sound cavity,a transducer placed so as to create, when energized a sound field in the sound cavity, a hollow probe, having a large end in communication with the sound cavity and a small end for placement at the ent-rance of the ear under test, such small end having diameter area chosen to match generally the diameter of the ear canal, and a microphone, placed within the test head, generator means, for generating an electrical signal having components over a suitable frequency range, such means connected to the transducer; and pro-cessor means, for processing the signal from the microphone to obtain a quantity related to the complex acoustic impedance of the ear, including means for providing an indication of a patholo-gical dip in a characteristic frequency region in the range of from 1.5 kHz to 5.5 kHz.
16. Apparatus for detecting pathologic ear conditions, com-prising A. an acoustic signal generator providing an acoustic output that sweeps over a frequency range of at least several kilohertz during a measurement, B. an acoustic waveguide having an input end coupled to receive the output of said generator and an output end positionable adjacent to and exteriorly of the outer canal of an ear being examined to thereby maintain said ear canal in communication with the atmosphere during measurement, said transducer transmitting acoustic waves into the outer canal of said ear r said output end characterized by an acoustic output impedance that is less than the acoustic input impedance of a typical canal to be examined; C. a microphone positioned to receive inputs from both the generator and from reflections from said ear, and providing an output indicative of the sum of said inputs, and D. means for displaying at least a portion of the output of said microphone for detecting departure of said output from the expected output for a normal ear.
17. Apparatus according to claim 16 in which said waveguide output end has an acoustic output impedance that is no greater than one-quarter the acoustic input impedance of said ear canal.
18. Apparatus according to claim 16 in which said waveguide, at the output end thereof, has a diameter no less than twice the diameter of said canal at the input thereof.
19. Apparatus according to claim 1.8 in which said generator provides an acoustic output that sweeps over a frequency of from at least 2 kHz to 7 kHz during a time interval not greater than one second.
20. Apparatus for detecting pathologic ear conditions, com-prising A. means for applying to an ear canal to be examined an incident acoustic signal that ranges over a frequency range of at least greater than a kilohertz while maintaining said ear substantially at atmospheric pressure; B. means for comparing said incident signal with signals reflected back through said ear canal to detect the occurrence of a resonance condition, and C. means providing an indication of a detected resonance.
21. Apparatus according to claim 20 in which the means providing an indication of a detected resonance comprises means for indicating the frequency and amplitude of the detected resonance.
22. Apparatus according to claim 21 in which said indication means comprises a first linearly disposed visual indication means for providing direct visual indication of the frequency of a detected resonance and a second linearly disposed visual indica-tion means for providing direct visual indication of the amplitude of a detected resonance.
23. Apparatus according to claim 22 in which said first visual indication means comprises a horizontally disposed row of light-emitting diodes and said second visual indication means comprises a vertically-disposed row of light-emitting diodes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US83/00380 | 1983-03-16 | ||
| PCT/US1983/000380 WO1983003192A1 (en) | 1982-03-16 | 1983-03-16 | Ear pathology diagnosis apparatus and method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1219330A true CA1219330A (en) | 1987-03-17 |
Family
ID=22174904
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000444478A Expired CA1219330A (en) | 1983-03-16 | 1983-12-30 | Ear pathology diagnosis apparatus and method |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS59500455A (en) |
| CA (1) | CA1219330A (en) |
| IT (1) | IT1214840B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10251790B2 (en) | 2013-06-28 | 2019-04-09 | Nocira, Llc | Method for external ear canal pressure regulation to alleviate disorder symptoms |
| US9039639B2 (en) | 2013-06-28 | 2015-05-26 | Gbs Ventures Llc | External ear canal pressure regulation system |
| US10568515B2 (en) * | 2016-06-21 | 2020-02-25 | Otonexus Medical Technologies, Inc. | Optical coherence tomography device for otitis media |
| US10760566B2 (en) | 2016-07-22 | 2020-09-01 | Nocira, Llc | Magnetically driven pressure generator |
| EP3585335B1 (en) | 2017-02-27 | 2024-05-08 | Nocira, LLC | Ear pumps |
-
1983
- 1983-03-16 JP JP50143483A patent/JPS59500455A/en active Granted
- 1983-12-30 CA CA000444478A patent/CA1219330A/en not_active Expired
-
1984
- 1984-03-16 IT IT8467252A patent/IT1214840B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| IT8467252A0 (en) | 1984-03-16 |
| IT1214840B (en) | 1990-01-18 |
| JPH0414007B2 (en) | 1992-03-11 |
| JPS59500455A (en) | 1984-03-22 |
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