Implanted Microphone AGC for Self-Voice Vibration Control

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Solution Overview

Problem

Implantable hearing instruments with implanted microphones face issues of vibration sensitivity, leading to distortion and feedback due to body sounds and self-voice vibrations, which existing methods struggle to address without affecting sound sensitivity or introducing noise.

Innovation Solution

An automatic gain control (AGC) circuit is implemented in the hearing instrument system to selectively reduce the gain of signals above a predetermined threshold, particularly for vibrations caused by the user's own voice, while maintaining sensitivity to desired acoustic signals, and to map the microphone's dynamic range into the signal processor's range, thereby enhancing signal-to-noise ratio and reducing distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the microphone gain is increased to improve sensitivity to airborne sound, then the sensitivity to vibration increases, but body sounds and self-voice vibrations saturate the amplifier stages causing distortion

Engineering Contradiction:

Improvesensitivity to airborne soundVSAvoidvibration sensitivity

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent implements dynamic gain control that adjusts the microphone amplification based on detected vibration levels. When vibration is detected above a threshold, the gain is reduced to prevent saturation and distortion. This dynamic adjustment allows the system to maintain high sensitivity for airborne sound under normal conditions while automatically reducing vibration sensitivity when needed, resolving the contradiction between these two sensitivity requirements.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If methods are used to reduce vibration sensitivity, then feedback and distortion are reduced, but sensitivity to desired airborne sound may be affected

Engineering Contradiction:

Improvevibration sensitivityVSAvoidsensitivity to airborne sound

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent applies different gain settings to different signal components based on their characteristics. The system identifies vibration signals versus airborne sound signals and applies appropriate gain control to each. This localized quality control ensures that vibration sensitivity is reduced only when vibration is detected, while maintaining full sensitivity for desired airborne sound, thus avoiding the trade-off present in global gain reduction methods.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If the dynamic range of the microphone is mapped to the signal processor range, then the signal-to-noise ratio is improved, but distortion may occur for signals above the processor range

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoiddistortion

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent performs preliminary gain control and signal conditioning before the signal enters the signal processor. By detecting vibration levels and adjusting gain in advance, the system ensures that signals are within the acceptable range for the processor, preventing distortion before it occurs. This preliminary action also optimizes the signal-to-noise ratio by setting appropriate gain levels, thus achieving both objectives simultaneously.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The AGC circuit effectively reduces unwanted vibrations and feedback, improving sound quality by dynamically adjusting gain based on signal magnitude and frequency, ensuring that desired sounds are amplified while minimizing distortion and noise.

Implementation Method 1

An automatic gain control (AGC) circuit is implemented in the hearing instrument system to selectively reduce the gain of signals above a predetermined threshold

Methodology Applied

Scientific EffectAutomatic Gain Control:

Implementation Method 2

a microphone diaphragm and amplified

Methodology Applied

Scientific EffectAcoustic detection:

Implementation Method 3

operation of a middle ear transducer used with a hearing instrument may create vibration that is transmitted by the skull to the microphone

Methodology Applied

Scientific EffectMechanical vibration:

Data Source

PatentUS8641595B2Automatic gain control for implanted microphone

Publication Date: 2014.02.04 COCHLEAR LIMITED

AI summary

An implantable hearing instrument is provided that reduces the response to unnaturally high vibrations (e.g., due to a patient's own voice), without necessarily or substantially affecting the response to desired signals. The implantable hearing instrument system is operative to selectively alter/lower the gain of signals that have a magnitude above a predetermined threshold. Signals having unnaturally large amplitudes (e.g., due to a patient's own voice) are amplified less than desired signals, so that a patient may experience a more representative sound.