JP6295988B2 - Sound field reproduction apparatus, sound field reproduction method, and sound field reproduction program - Google Patents

Description

  The present invention relates to a sound field reproduction device, a sound field reproduction method, and a sound field reproduction program.

  Patent Document 1 has conventionally known a method using a listener's head related transfer function HRTF (Head Related Transfer Function) as a method of localizing a sound image outside the head (for example, see Patent Document 1). When a headphone or an earphone is used, the inverse characteristics of the head-related transfer function from the virtual sound source to both ears of the listener and the ear canal transfer function (ECTF) are convolved with the reproduction signal. By doing so, it is possible to cancel the characteristics of the headphones or earphones and reproduce the sound field as if sound is heard from the direction of the virtual sound source even though sound is emitted from the vicinity of the ear. The ear canal transfer function ECTF is measured by inserting a measurement microphone into the listener's ear canal or substituting a dummy head.

JP 2002-209300 A

  However, the ideal sound image localization is in a state where the external auditory canal is opened, but in actual measurement, the external ear canal is closed because the measurement is performed with headphones or earphones attached. As a result, resonance occurs in the ear canal, and a peak or dip occurs at a specific frequency. As a result of convolution of the inverse characteristic of the ear canal transfer function (also referred to as the ear canal correction function) with the reproduction signal, the sound quality on hearing may be deteriorated. Also, in the reproduction of a three-dimensional sound field by a speaker using a head-related transfer function, resonance may occur due to the influence of reflection in the measurement space, etc., resulting in deterioration of sound quality. It is difficult to detect the peak or dip generated by resonance from the waveform of the reproduction signal. Therefore, there is a possibility that the sound field cannot be properly reproduced.

  The present invention has been made in view of the above points, and an object thereof is to provide a sound field reproduction device, a sound field reproduction method, and a sound field reproduction program that can appropriately reproduce a sound field.

  A sound field reproduction device according to one aspect of the present invention is output from a sweep signal generation unit that generates a sweep signal whose frequency changes, an output unit that outputs the sweep signal to a listener, and the output unit. A setting storage unit that stores a frequency at which the volume of the sweep signal changes according to an operation from a listener who listens to the sweep signal, and a frequency that is swept in the vicinity of the frequency stored in the setting storage unit. Sometimes, an input unit that receives a volume adjustment operation by a listener, a filter coefficient calculation unit that calculates a filter coefficient based on information when the volume is adjusted so that the volume is constant in the vicinity of the frequency, A filter unit that performs a filter process using the filter coefficient on a sound signal and outputs the signal to the output unit.

  A sound field reproduction method according to an aspect of the present invention includes a step of generating a sweep signal whose frequency changes, a step of outputting the sweep signal to a listener, and an operation from a listener who listens to the sweep signal. Accordingly, storing a frequency at which the volume of the sweep signal changes, receiving a volume adjustment operation by a listener when the frequency is swept in the vicinity of the stored frequency, and the vicinity of the frequency A step of calculating a filter coefficient based on information when the volume is adjusted so that the volume is constant in step, a step of performing a filtering process on the sound signal using the filter coefficient, and a filtering process And outputting the performed sound signal to the listener.

  A program according to an aspect of the present invention includes a step of generating a sweep signal whose frequency changes, a step of outputting the sweep signal to a listener, and an operation from a listener who listens to the sweep signal. Storing a frequency at which the volume of the sweep signal changes; receiving a volume adjustment operation by a listener when the frequency is swept in the vicinity of the stored frequency; and a volume in the vicinity of the frequency. A filter coefficient is calculated based on information when the volume is adjusted to be constant, a filter process using the filter coefficient is performed on the sound signal, and the filter process is performed. And outputting the sound signal to the listener.

  According to the present invention, it is possible to provide a sound field reproduction device, a sound field reproduction method, and a sound field reproduction program that can appropriately reproduce a sound field.

It is a block diagram which shows the sound field reproducing | regenerating apparatus which concerns on this Embodiment 1. FIG. It is a figure which shows an isosensitive curve. 3 is a flowchart showing a sound field reproduction method according to the first embodiment. It is a figure for demonstrating the sweep operation | movement and the change of a frequency characteristic. It is a figure for demonstrating the sweep operation | movement and the change of a frequency characteristic. It is a figure for demonstrating the sweep operation | movement and the change of a frequency characteristic. It is a figure for demonstrating the sweep operation | movement and the change of a frequency characteristic. It is a block diagram which shows the sound field reproduction apparatus which concerns on this Embodiment 2.

An outline of the sound field reproducing apparatus according to the present embodiment will be described.
The sound field reproduction device according to the present embodiment measures an individual's head-related transfer characteristic (also referred to as a head-related transfer function) or an ear-canal transfer characteristic (also referred to as an ear-canal transfer function), and uses such characteristics to perform an out-of-head localization or the like. Sound field reproduction is realized. Specifically, in the sound field reproduction device, the influence of reflection in the space at the time of measuring the transfer characteristic and the influence of resonance caused by the blockage of the ear canal are eliminated to improve sound quality degradation.

  In the present embodiment, sound field processing such as out-of-head localization is realized using the head-related transmission characteristics from the speaker to the listener's ears, or the ear-canal transmission characteristics when headphones or earphones are worn. In spatial transmission characteristics such as head transmission characteristics or ear canal transmission characteristics, resonance may occur due to reflection in the measurement space, and peaks or dips may occur in high frequencies. In the measurement of the ear canal transmission characteristics, resonance may occur when the ear canal is blocked, and a peak or dip may occur in a high frequency range. This is a personal characteristic that varies from person to person, and can only be perceived by the listener, and is difficult to automatically correct.

  Therefore, a frequency sweep signal (sweep signal) whose frequency gradually changes is used. While listening to the frequency sweep signal, the listener operates the buttons, etc., at the part where the volume feels greatly changed. By doing in this way, the position (frequency) of a peak and a dip can be specified. A filter such as a notch filter or a peaking filter is applied around the peak or dip frequency. In this way, unnecessary resonance can be removed and corrected to a flat frequency characteristic.

  After specifying the position (frequency) of the peak and dip by the above operation, the surrounding frequencies may be repeatedly swept. Then, the listener can adjust the peak level of the filter so that the sound volume can be heard at a constant level, thereby enabling further fine correction.

  Since the auditory strength of the sound varies depending on the sound frequency due to the characteristics of human hearing, it is preferable to apply AGC (automatic gain control) in the out-of-head localization processing. In this way, the listener can listen to the sound with a certain auditory strength regardless of the frequency of the sound frequency, and the button operation when identifying the position of the peak or dip is appropriate. It becomes possible.

Embodiment 1 FIG.
FIG. 1 shows a sound field reproducing apparatus 100 according to the present embodiment. FIG. 1 is a block diagram of the sound field reproduction device 100. The sound field reproduction device 100 reproduces a sound field for the listener U wearing the headphones 19. Therefore, the sound field reproduction device 100 includes a sweep signal generation unit 11, a music signal reproduction unit 12, an out-of-head localization processing unit 13, an AGC (Auto Gain Control) processing unit 14, and a variable filter unit (filter unit) 15. A filter coefficient calculation unit 16, a setting storage unit 17, an input unit 18, and a headphone (output unit) 19.

  The sound field reproduction apparatus 100 according to the present embodiment is an information processing apparatus such as a personal computer, and includes processing means such as a processor, storage means such as a memory and a hard disk, a liquid crystal monitor such as an organic EL display and a plasma display, and the like. Display means, touch panel, buttons, keyboard, mouse and other input means, and output means connected to speakers and headphones. Alternatively, the sound field reproduction device 100 may be a smart phone or a tablet PC. Further, the sound field reproducing apparatus 100 incorporates a processing unit such as a processor and a storage unit such as a memory in a speaker or a headphone that is an output unit, and the headphone or the like includes a display unit such as a liquid crystal monitor and an input such as a touch panel. It is good also as a structure which can connect a means.

  The sweep signal generator 11 generates a frequency sweep signal whose frequency changes. The sweep signal generator 11 outputs a sine wave that gradually sweeps a preset sweep range as a frequency sweep signal. The frequency sweep signal is, for example, a pure tone and a signal whose center frequency gradually changes. The sweep signal generator 11 outputs a frequency sweep signal to the out-of-head localization processing unit 13. The frequency sweep signal is subjected to processing described later and is output from the headphones 19. The frequency sweep signal increases in frequency at a constant speed. Further, the frequency sweep signal may continuously increase in frequency, or may increase in frequency step by step. Alternatively, the frequency may be gradually lowered. The frequency sweep signal may be a stereo signal.

  The music signal reproduction unit 12 reproduces a music signal recorded in advance on a memory or a disk. The music signal reproducing unit 12 may not be provided inside the sound field reproducing device 100, and a music signal from an external sound source may be input to the out-of-head localization processing unit 13. For example, the music signal may be a stereo signal output from an external CD player or the like. The music signal is finally output from the headphones 19 after being subjected to a filtering process described later. The music signal is, for example, a stereo reproduction signal obtained by digitizing a musical performance or a voice performance, and is output from the left and right units of the headphones 19. Note that the music signal is not limited to a signal obtained by digitizing a musical instrument or a voice performance, but may be a signal obtained by digitizing a sound that a human can hear by hearing, such as conversation, animal calls, and ripples.

  During music playback, the music signal playback unit 12 outputs the music signal to the out-of-head localization processing unit 13, and the sweep signal generation unit 11 does not generate a frequency sweep signal. On the other hand, when measuring the filter coefficient for sound quality adjustment, the sweep signal generator 11 outputs the frequency sweep signal to the out-of-head localization processing unit 13, and the music signal reproduction unit 12 does not reproduce the music signal. That is, a frequency sweep signal is output from the headphones 19 and measurement is performed to eliminate resonance caused by personal characteristics such as the external auditory canal shape. As described above, either the music signal or the frequency sweep signal is input to the out-of-head localization processing unit 13. Hereinafter, the process of outputting a frequency sweep signal in order to measure the filter coefficient will be mainly described.

  The out-of-head localization processing unit 13 performs convolution processing on the frequency sweep signal using the ear canal transfer characteristic. Specifically, the inverse characteristic of the ear canal transmission characteristic measured in advance (also referred to as the ear canal correction function) is convolved with the frequency sweep signal. The out-of-head localization processing unit 13 outputs the frequency sweep signal subjected to the convolution processing to the AGC processing unit 14. As will be described later, the out-of-head localization processing unit 13 convolves the inverse characteristic of the ear canal transmission characteristic with the music signal.

  The AGC processing unit 14 performs processing to keep a signal level (roundness level) representing the auditory intensity of the sound of the frequency sweep signal constant. Here, even if a sound with a high frequency and a sound with a low frequency have the same sound pressure, a difference occurs in the auditory strength of the sound that human hearing feels. An isosensitivity curve (loudness curve) representing this characteristic is shown in FIG. In FIG. 2, the horizontal axis represents frequency (Hz) and the vertical axis represents sound pressure level (dB). Each curve shows the relationship between the frequency and the sound pressure level for each signal level representing the auditory intensity of the sound. For example, when it is desired to keep the acoustic intensity of sound constant at 60 phon, it can be understood from this figure that the sound pressure level needs to be changed according to the frequency. Therefore, when performing out-of-head localization processing on the frequency sweep signal, the AGC processing unit 14 adjusts the gain according to the isosensitive curve. The gain in the AGC processing unit 14 changes according to the sound volume, that is, the sound pressure level or the frequency. When the AGC processing unit 14 performs AGC (automatic gain control) processing, the gain is adjusted so that the frequency sweep signal has a constant signal level. Thereby, the listener U can listen to the sound at a constant signal level regardless of the frequency of the sound. The frequency sweep signal subjected to AGC processing by the AGC processing unit 14 is output to the variable filter unit 15.

  The variable filter unit 15 reads out the filter coefficient calculated by the filter coefficient calculation unit 16 and sets a filter such as a notch filter and a peaking filter. The variable filter unit 15 performs filter processing on the frequency sweep signal using the set filter. In the initial state, a filter having a flat characteristic is set in the filter coefficient calculation unit 16. Therefore, the frequency sweep signal from the AGC processing unit 14 is output to the headphones 19 as it is.

  Here, the variable filter unit 15 outputs the frequency sweep signal to the headphones 19 as it is. The headphones 19 output a frequency sweep signal toward the listener U. The headphones 19 are stereo headphones, and output frequency sweep signals to the left and right ears of the listener U, respectively. The listener U listens to the frequency sweep signal output from the headphones 19.

  The listener U confirms whether or not the volume changes rapidly while listening to the frequency sweep signal subjected to the out-of-head localization process. The frequency range to be swept is set in advance. In the measurement of the ear canal transfer function, resonance occurs in a high frequency range, and therefore, the sweep range for sweeping the frequency sweep signal is 8 kHz to 20 kHz. Of course, the sweep range is not limited to 8 to 20 kHz. For example, the sweep range may be 5 kHz to 20 kHz. The sweep range is preferably set arbitrarily for each measurement environment because the frequency at which a peak / dip tends to occur differs depending on the measurement environment. Of course, the entire reproduction frequency region of the headphones 19 may be set as the sweep range. Further, the listener U may specify the sweep range.

  When the listener U is listening to the frequency sweep signal and the volume changes rapidly, the input unit 18 is operated. The input unit 18 includes an input device such as a touch panel, a keyboard, a mouse, a push button, a lever, or a dial. For example, the listener U presses a frequency determination button provided in the input unit 18 after confirming a sudden change in volume while listening to the frequency sweep signal. Then, the input unit 18 accepts a button operation by the listener U and outputs a signal corresponding to the operation to the setting storage unit 17.

  The frequency currently being swept is input from the sweep signal generator 11 to the setting storage unit 17. The setting storage unit 17 includes a memory or the like, and stores the frequency of the frequency sweep signal when the frequency determination button is pressed. That is, the setting storage unit 17 stores the frequency at which the volume has changed abruptly. For example, the setting storage unit 17 stores a frequency at which the volume is suddenly reduced as a notch frequency. Or the setting memory | storage part 17 memorize | stores the frequency in which the sound volume increased rapidly as a peak frequency. The setting storage unit 17 stores the frequency at which the volume of the frequency sweep signal changes in response to an operation from the listener U who listens to the frequency sweep signal output from the headphones 19.

  Then, the setting storage unit 17 outputs the stored frequency to the sweep signal generation unit 11. Then, the sweep signal generator 11 generates a frequency sweep signal that slowly sweeps the vicinity of the inputted frequency. That is, the sweep signal generator 11 slowly changes the frequency of the frequency sweep signal in the vicinity of the notch frequency or peak frequency. The listener U listens to the frequency sweep signal. Then, the input unit 18 is operated so that the volume is constant.

  For example, the input unit 18 includes a lever and a dial for adjusting the volume. By operating the input unit 18 by the listener U, the volume of the sound output from the headphones 19 can be adjusted. The setting storage unit 17 stores the volume adjusted by the listener U. When the frequency is swept in the vicinity of the frequency stored in the setting storage unit 17, the input unit 18 accepts a volume adjustment operation by the listener U.

  The setting storage unit 17 stores the volume in association with the frequency. That is, the peak or dip frequency is associated with the volume adjusted at that frequency. The filter coefficient calculation unit 16 calculates a filter coefficient based on the frequency and volume stored in the setting storage unit 17. The filter coefficient calculation unit 16 calculates filter coefficients in real time using the already determined frequency and volume.

  The filter coefficient calculated in real time by the filter coefficient calculation unit 16 is set in the variable filter unit 15. As a result, the characteristics of the variable filter that was flat in the initial state change. The filter coefficient calculation unit 16 applies a filter coefficient to the frequency sweep signal subjected to the out-of-head localization process. By doing so, the peak level of the frequency sweep signal subjected to out-of-head localization processing varies.

  Then, the listener U operates the input unit 18 when it is determined that the frequency sweep signal has audibly reached a certain level by the volume operation. For example, when the listener U reaches a certain level, the adjustment completion button is pressed. In this way, the peak level at which the volume is constant is determined. The setting storage unit 17 stores the filter coefficient and the volume at the time when the adjustment completion button is pressed as level information. The filter coefficient calculation unit 16 calculates a final filter coefficient according to the level information. Based on the level information when the volume is adjusted so that the volume is constant in the vicinity of the frequency stored in the setting storage unit 17, the filter coefficient calculation unit 16 calculates the filter coefficient.

  The final filter coefficient calculated from the frequency and level information is set in the variable filter unit 15. In this way, the measurement for eliminating resonance due to personal characteristics is completed. When the measurement is completed, the input to the out-of-head localization processing unit 13 is switched from the sweep signal to the music signal. By doing so, a normal music playback mode is achieved, and sound field playback using a music signal becomes possible. That is, an out-of-head localization process in the out-of-head localization processing unit 13 and a filter process in the variable filter unit 15 are performed on the music signal.

  The out-of-head localization processing unit 13 performs convolution on the music signal using the ear canal correction function. The variable filter unit 15 performs a filter process on the music signal subjected to the convolution process using the filter coefficient set by using the frequency sweep signal described above, and outputs it to the headphones 19. Note that the AGC processing in the AGC processing unit 14 is not performed during music reproduction. In addition, during the measurement using the frequency sweep signal, the out-of-head localization processing unit 13 may not perform the convolution process on the frequency sweep signal.

  In this way, the frequency sweep signal is heard by the listener U, and the peak frequency or dip frequency is specified. By doing so, resonance according to the personal characteristics of the listener U can be eliminated. Furthermore, a filter coefficient for correcting a peak or dip caused by the measurement environment or the like is set. Therefore, it is possible to appropriately reproduce the sound field.

  Next, with reference to FIGS. 3 to 7, the sound quality adjustment in the sound field reproduction method according to the present embodiment will be described. FIG. 3 is a flowchart showing sound quality adjustment in the sound field reproduction method. 4 to 7 are graphs showing changes in frequency characteristics in the adjustment operation. 4-7, a horizontal axis is a frequency and a vertical axis | shaft is a sound volume listened by the listener U. FIG.

  When measurement is started, the frequency of the frequency sweep signal is swept in order to examine the center frequency of the peak and dip (S1). Here, the sweep signal generator 11 sweeps the sweep range from 8 kHz to 20 kHz as shown in FIG. Here, only the high frequency side of the listening range that the listener U can listen to is swept. The listener U determines whether or not a sudden volume difference is felt while listening to the frequency sweep signal (S2). That is, it is determined whether or not the listener U feels a volume difference in the frequency sweep signal output at a constant level. If no sudden volume difference is felt (NO in S2), the frequency is continuously swept.

  When a sudden volume difference is felt (YES in S2), the listener U presses the frequency determination button of the input unit 18 (S3). That is, the listener U presses the frequency determination button at the timing when the volume becomes maximum or minimum. Then, the setting storage unit 17 stores the frequency at the time when the frequency determination button is pressed (S4). As shown in FIG. 5, the frequency at the time when the frequency determination button is pressed is determined as the center frequency of the peak or dip.

  Next, it repeatedly sweeps slowly around the stored frequency (S5). That is, as shown in FIG. 6, the vicinity of the stored frequency is set as the level adjustment range. The sweep signal generator 11 outputs a frequency sweep signal for sweeping the level adjustment range including the center frequency. The sweep speed in the level adjustment range is slower than the sweep speed in S1. That is, the sweep signal generator 11 sweeps the level adjustment range more slowly than the sweep in the sweep range. In this way, a part of the 8-20 kHz sweep range is extracted and slowly swept as a level adjustment range.

  Then, while the level adjustment range is slowly swept, the listener U operates the volume (S6). At a frequency where there is a dip, the volume heard by the listener U is small. Therefore, as shown in FIG. 6, the listener U increases the volume so that the audible volume becomes constant. On the other hand, when there is a peak in the frequency characteristic, the listener U decreases the volume at the center frequency in order to keep the volume constant. The listener U adjusts the volume level while listening to the frequency sweep signal. By doing so, it is possible to adjust the volume at which the listener U listens at the center frequency.

  The setting storage unit 17 stores the operated volume, and the filter coefficient calculation unit 16 calculates the filter coefficient based on the stored volume and frequency (S7). The filter coefficient calculated in real time is set in the variable filter unit 15 (S8). By doing so, the characteristics of the filter change. That is, the filter coefficient at the peak frequency or notch frequency changes. The variable filter unit 15 performs a filtering process on the frequency sweep signal and outputs the filtered signal to the headphones 19. That is, the variable filter unit 15 outputs a frequency sweep signal multiplied by the filter coefficient to the headphones 19.

  The headphones 19 output the filtered frequency sweep signal toward the listener U. The listener U determines whether or not the frequency sweep signal output from the headphones 19 can be heard at a certain level (S9). That is, when the sweep is performed within the level adjustment range shown in FIG. 6, the listener U determines whether or not the volume is constant regardless of the frequency.

  If it is determined that the frequency sweep signal cannot be heard at a certain level (NO in S9), the processing from step S5 is repeated until it can be heard at a certain level. That is, the listener adjusts the volume while listening to the sweep signal in the level adjustment range. Therefore, as shown in FIG. 7, the processing from S5 to S9 is repeated until the frequency sweep signal is heard at a constant level. When it is determined that the frequency sweep signal is heard at a certain level (YES in S9), the listener U presses the adjustment completion button. Thereby, the setting memory | storage part 17 memorize | stores the volume and filter coefficient when an adjustment completion button is pushed as level information (S10). By doing so, as shown in FIG. 7, the sound can be heard at a substantially constant volume regardless of the frequency.

  As shown in FIG. 7, when the volume becomes constant, the filter coefficient calculation unit 16 calculates a final filter coefficient from the center frequency and the level information (S11). That is, the setting storage unit 17 stores the level information corresponding to the volume when the volume becomes constant in the level adjustment range in association with the frequency. Then, the filter coefficient calculation unit 16 calculates the filter coefficient at the frequency based on the frequency and level information stored in the setting storage unit 17. Thereafter, the final filter coefficient is set in the variable filter unit 15 (S12). In this way, the filter coefficient measurement is completed.

  At the time of music reproduction, the final filter coefficient is set in the variable filter unit 15. When reproducing a music signal, after the out-of-head localization processing unit 13 performs out-of-head localization processing on the music signal, the variable filter unit 15 performs a filtering process on the music signal. That is, the music signal is multiplied by the filter coefficient included in the filter set in the variable filter unit 15. Then, the headphones 19 output the filtered music signal to the listener U. That is, the headphone 19 outputs the music signal subjected to the out-of-head localization process and the filter process to the listener U, thereby reproducing the sound field.

  In this way, the filter coefficient is obtained by measurement using the sweep signal. Then, by filtering with a filter including the obtained filter coefficient, it is possible to eliminate resonance caused by the individual characteristics of the ear canal shape. Therefore, the music signal subjected to the out-of-head localization process can be corrected appropriately. Therefore, even when the headphones 19 are used, the sound field can be appropriately reproduced. In the above description, the sound field reproduction device using the headphones 19 is shown, but the same processing can be performed for a sound field reproduction device using earphones.

  In the above description, the case where there is a dip in the frequency characteristic has been described. However, the sound quality can be similarly adjusted when there is a peak. That is, the volume may be lowered in S6 so that the volume at the peak frequency is lowered. As a result, the sound quality can be adjusted so that the volume at the peak frequency is reduced.

  Also, when there are two or more peak frequencies and dip frequencies, the volume may be adjusted for each frequency. That is, the volume is adjusted for each peak and dip included in the sweep range. Then, the filter coefficient calculation unit 16 obtains the filter coefficient in accordance with the level information when the volume is adjusted and the frequency corresponding to the level information. By doing so, it is possible to set an appropriate filter, so that the sound field can be appropriately reproduced. Further, the width of the notch filter or peaking filter may be adjusted.

  When the frequency presented on the display unit is displayed, it is easy for the listener U to understand. The speed at which the frequency sweep signal generator 11 sweeps the frequency may be adjusted by the listener.

Embodiment 2. FIG.
The sound field reproduction apparatus according to this embodiment will be described with reference to FIG. FIG. 8 is a block diagram showing a sound field reproduction device 200 according to the second embodiment. In the present embodiment, the sound field is reproduced using the speaker 29 instead of the headphones 19. That is, a speaker 29 is used instead of the headphones 19.

  The speaker 29 is a speaker having a plurality of channels such as a stereo speaker and a surround speaker. Further, in the present embodiment, a pseudo surround processing unit 23 is provided instead of the out-of-head localization processing unit 13 of the first embodiment. Since the configuration other than the pseudo surround processing unit 23 is the same as that of the first embodiment, the description thereof is omitted.

  The sweep signal generated by the sweep signal generation unit 21 and the music signal reproduced by the music signal reproduction unit 22 are input to the pseudo surround processing unit 23. The pseudo-surround processing unit 23 is set with a head-related transfer characteristic (also referred to as a head-related transfer function) measured in advance. The pseudo surround processing unit 23 performs a convolution process of the head-related transfer characteristic (also referred to as a head-related transfer function). The pseudo surround processing unit 23 outputs the frequency sweep signal subjected to the convolution processing to the AGC processing unit 24. The processes in the AGC processing unit 24, variable filter unit 25, filter coefficient calculation unit 26, setting storage unit 27, and input unit 28 are the AGC processing unit 14, variable filter unit 15, filter coefficient calculation unit 16, and setting storage of the first embodiment. The same as the unit 17 and the input unit 18. Therefore, as in the first embodiment, the frequency of the notch or peak is determined, and the filter coefficient calculation unit 26 calculates the filter coefficient.

  A filter having the calculated filter coefficient is set in the variable filter unit 25. The speaker 29 outputs a frequency sweep signal multiplied by the filter coefficient toward the listener U. The listener adjusts the volume in the same manner as in the first embodiment while listening to the frequency sweep signal output from the speaker 29. When the final filter coefficient is calculated, the input to the pseudo surround processing unit 23 is switched from the frequency sweep signal to the music signal. The pseudo surround processing unit 23 and the variable filter unit 25 process the music signal. A music signal that has been processed by the pseudo surround processing unit 23 and the variable filter unit 25 is output from the speaker 29.

  In the present embodiment, after the pseudo surround processing unit 23 convolves the head-related transfer characteristic with the music signal, the variable filter unit 15 performs the filtering process on the music signal. By doing in this way, the surround sound field output from the speaker 29 can be reproduced. Furthermore, a filter coefficient for correcting a peak or dip caused by the measurement environment or the like is set. Therefore, it is possible to appropriately reproduce the sound field.

  Part or all of the signal processing may be executed by a computer program. The programs described above can be stored and provided to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)). The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

11, 21 Sweep signal generation unit 12, 22 Music signal reproduction unit 13 Out-of-head localization processing unit 14, 24 AGC processing unit 15, 25 Variable filter unit (filter unit)
16, 26 Filter coefficient calculation unit 17, 27 Setting storage unit 18, 28 Input unit 19 Headphone (output unit)
23 Pseudo surround processing unit 29 Speaker 100, 200 Sound field reproduction device

Claims (3)

A sweep signal generator for generating a sweep signal whose frequency changes;
An output unit for outputting the sweep signal to a listener;
A setting storage unit that stores a frequency at which the volume of the sweep signal changes according to an operation from a listener who listens to the sweep signal output from the output unit;
An input unit that accepts a volume adjustment operation by a listener when the frequency is swept in the vicinity of the frequency stored in the setting storage unit;
A filter coefficient calculation unit that calculates a filter coefficient based on information when the volume is adjusted so that the volume is constant in the vicinity of the frequency;
A sound field reproduction apparatus comprising: a filter unit that performs a filter process using the filter coefficient on a sound signal and outputs the signal to the output unit. Generating a sweep signal of varying frequency;
Outputting the sweep signal to a listener;
Storing a frequency at which the volume of the sweep signal changes in response to an operation from a listener who listens to the sweep signal;
Receiving a volume adjustment operation by a listener when the frequency is swept in the vicinity of the stored frequency;
Calculating a filter coefficient based on information when the volume is adjusted so that the volume is constant in the vicinity of the frequency;
Filtering the sound signal using the filter coefficient;
A sound field reproduction method comprising: outputting the filtered sound signal to the listener. Generating a sweep signal of varying frequency;
Outputting the sweep signal to a listener;
Storing a frequency at which the volume of the sweep signal changes in response to an operation from a listener who listens to the sweep signal;
Receiving a volume adjustment operation by a listener when the frequency is swept in the vicinity of the stored frequency;
Calculating a filter coefficient based on information when the volume is adjusted so that the volume is constant in the vicinity of the frequency;
Filtering the sound signal using the filter coefficient;
A program for causing a computer to execute the step of outputting the filtered sound signal to the listener.