Implanted Hearing Instrument Adaptive Vibration Cancellation
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Solution Overview
Problem
Implanted hearing instruments face challenges in distinguishing between desirable airborne sound signals and undesirable vibration signals caused by bone conduction, leading to distortion and feedback, particularly due to the sensitivity of implanted microphones to biological noise and mechanical feedback.
Innovation Solution
The use of motion sensors, such as acceleration and velocity sensors, to differentiate between desirable and undesirable signals by generating a motion signal that is processed to reduce vibration sensitivity, involving signal processing techniques like scaling, phase shifting, and filtering to subtract noise from the microphone output, and the implementation of adaptive filters to adjust for changing environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the implanted microphone is positioned to facilitate receipt of acoustic signals, then sound sensitivity is improved, but vibration sensitivity increases causing body sounds and bone conduction to saturate amplifier stages
Solution Approach 1:
The patent separates the harmful vibration signal from the useful acoustic signal by using two independent sensing paths: a motion sensor (accelerometer) detects vibrations while the microphone detects acoustic signals. This segmentation allows selective processing to remove vibration components while preserving sound sensitivity.
Solution Approach 2:
The motion sensor acts as an intermediary device that indirectly measures the vibration components affecting the microphone. By measuring acceleration and integrating it to obtain velocity and position signals, the system creates an intermediary representation of vibrations that can be subtracted from the microphone output without directly interfering with acoustic signal detection.
2Reliability
If motion sensors and signal processing are used to reduce vibration sensitivity, then feedback and biological noise are reduced, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical vibration isolation structures with electronic signal processing. Instead of using mechanical dampers or isolation mechanisms, the system uses digital signal processing to subtract vibration components from the acoustic signal, reducing mechanical complexity while improving reliability.
Solution Approach 2:
The system implements feedback by continuously monitoring motion sensor output and using it to adjust the cancellation signal in real-time. The processed motion signal is fed back to the subtraction stage, creating a closed-loop system that adaptively reduces vibration interference while maintaining system stability.
3Adaptability or versatility
If adaptive filters are implemented to adjust for changing environmental conditions, then signal quality is maintained across varying conditions, but processing requirements and power consumption increase
Solution Approach 1:
The patent implements dynamic adaptation through adaptive filtering that automatically adjusts filter coefficients based on changing environmental conditions. The system transitions from static to dynamic operation, where the cancellation parameters are continuously optimized to match current acoustic and vibration conditions, improving adaptability while managing computational load.
Solution Approach 2:
The system changes processing parameters (filter coefficients, integration constants, cancellation weights) based on environmental conditions such as user activity, head position, and acoustic environment. By dynamically adjusting these parameters rather than using fixed values, the system maintains signal quality across varying conditions while optimizing power consumption through selective reprocessing.
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
This approach effectively reduces the system's response to unwanted vibrations and feedback, improving the quality of audio signals for implantable hearing instruments by minimizing noise and maintaining sensitivity to airborne sounds, even in varying environmental conditions.
Implementation Method 1
undesirable signals, caused by bone vibration, of an implant housing and skin being accelerated by motion of the underlying bone, which will result in the inertia of the overlying skin exerting a force on the microphone diaphragm
Implementation Method 2
involving signal processing techniques like scaling, phase shifting, and filtering to subtract noise from the microphone output
Data Source
AI summary
The invention is directed to an implanted microphone having reduced sensitivity to vibration. In this regard, the microphone differentiates between the desirable and undesirable vibration by utilizing at least one motion sensor to produce a motion signal when an implanted microphone is in motion. This motion signal is used to yield a microphone output signal that is less vibration sensitive. In a first arrangement, the motion signal may be processed with an output of the implantable microphone transducer to provide an audio signal that is less vibration-sensitive than the microphone output alone. Specifically, the motion signal may be scaled to match the motion component of the microphone output such that upon removal of the motion signal from the microphone output, the remaining signal is an acoustic signal.