Title: Proposal for Development of Low-Power Noise-Canceling Headphones/ Hearing Protection Device

1. Introduction

The objective of this proposal is to develop a noise-canceling headphone/hearing protection device that is capable of amplifying low-level sounds, suppressing harmful noise above 82dB, utilizing a rechargeable lithium-ion battery with a lifespan of at least 150 hours, and incorporating an auto shut-off feature to save battery life. The device will leverage cutting-edge audio Digital Signal Processing (DSP) to provide a clear and high-quality audio experience.

2. Required Components

a. Chipset/Development Board

• Recommended Chipset: Analog Devices ADAU1761
  • The ADAU1761 is a low power, stereo audio codec with integrated digital audio processing that includes a SigmaDSP 28-/56-bit audio DSP.
  • It supports multiple power supply voltages to maximize efficiency.
  • It has an integrated PLL that supports a wide range of clock rates and can interface with a variety of microcontrollers.

b. Microphones

• Two MEMS microphones for noise sampling and active noise cancellation.
• Recommended Microphone: Knowles SPH0645LM4H-B
  • This is an I2S MEMS microphone with a 24-bit precision and a 50Hz to 20kHz frequency response range.

c. Rechargeable Lithium-Ion Battery

• Minimum capacity: 2000mAh (to ensure at least 150 hours of operation).
• Include a battery management circuit for safe charging and discharging.

d. Power Management Circuitry

• A low-dropout regulator to ensure a constant voltage supply to the chipset.
• A charging circuit compatible with the lithium-ion battery.

e. Audio Drivers

• Use high-sensitivity audio drivers for better performance at low power consumption levels.
• Recommended Driver: Knowles Balanced Armature Drivers.

f. Control Unit

• A small microcontroller to manage the features such as auto shut-off.
• Recommended Microcontroller: Atmel ATtiny85

g. Additional Components

• Rotary encoder or capacitive touch sensor for volume and mode control.
• LED indicators for battery status and mode.
• External buttons for power and noise-cancelation features.

3. Features and Implementation

a. Amplify Low-level Sounds

• The ADAU1761’s integrated DSP will be programmed to amplify ambient sounds, while the MEMS microphones capture the environmental sounds.

b. Suppress Harmful Noise above 82 dB

• The DSP algorithms will monitor the sound levels and reduce the amplitude of sounds above 82 dB to protect the user's hearing.

c. Rechargeable Lithium-Ion Battery

• A 2000mAh lithium-ion battery will provide power to the device, ensuring at least 150 hours of operation.

d. Auto Shut-off Feature

• The ATtiny85 microcontroller will be programmed to monitor user activity and automatically power down the headphones after a set period of inactivity to conserve battery life.

4. Design Considerations

   • Ergonomic design for comfortable use over extended periods.
   • Durable materials for wear and tear.
   • Waterproofing and dustproofing to IPX5 or better.
   • Compliance with relevant safety and electronics standards.

5. Conclusion

This proposal outlines a robust, low-power solution for the development of noise-canceling headphones/hearing protection devices with the ability to amplify low-level sounds and suppress harmful noise. The integration of modern DSP technology, high-quality audio drivers, and MEMS microphones, coupled with an efficient power management system, will make this device highly effective and user-friendly.