Adaptive Filter Noise Cancellation for Hearing Device Feedback
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Solution Overview
Problem
Medical devices, particularly hearing prostheses, face challenges in effectively reducing noise and feedback due to body vibrations and accelerations, which can lead to oscillation and reduced speech intelligibility.
Innovation Solution
Implementing an adaptive filter system that combines signals from a microphone and an accelerometer to cancel noise and feedback, using an adaptive algorithm to adjust filters and reduce unwanted vibrations, thereby improving signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional noise cancellation methods are used in hearing devices, then feedback reduction is attempted, but body vibrations and accelerations cause oscillation and reduced speech intelligibility
Solution Approach 1:
The patent divides the noise cancellation system into separate functional modules: a first adaptive filter for canceling feedback from the actuator, and a second adaptive filter for canceling body vibrations and accelerations. This segmentation allows each filter to specialize in specific noise sources, improving overall effectiveness while maintaining speech intelligibility.
Solution Approach 2:
The patent introduces an intermediary signal processing chain where the microphone signal is processed through multiple filter stages. The first adaptive filter uses the actuator signal as reference, and the second adaptive filter uses the accelerometer signal as reference, creating an intermediary processing layer that effectively separates and cancels different noise components without compromising the desired audio signal.
2Object-affected harmful factors
If adaptive filter system is implemented to cancel noise and feedback, then signal quality is improved, but device complexity increases
Solution Approach 1:
The patent implements a multi-functional signal processing system where the same adaptive filter framework handles multiple noise cancellation tasks. The first adaptive filter addresses feedback noise, while the second adaptive filter addresses body vibrations, allowing a single system architecture to perform multiple specialized functions without requiring entirely separate systems.
Solution Approach 2:
The patent employs feedback mechanisms where the output of each adaptive filter is fed back to adjust the filter coefficients dynamically. The first adaptive filter uses feedback from the actuator signal, and the second uses feedback from the accelerometer signal, enabling continuous optimization of noise cancellation performance while adapting to changing acoustic and vibrational conditions.
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 system effectively reduces noise and feedback, enhancing speech intelligibility and providing a more natural listening experience by minimizing oscillations and maintaining a balanced signal-to-noise ratio.
Implementation Method 1
an accelerometer operative to receive mechanical energy and generate an accelerometer output signal
Data Source
AI summary
A system for reducing noise in a drive signal of a hearing device, including a microphone operative to receive sound and generate a microphone output signal and an adaptive filter apparatus that receives a signal from a transducer separate from the microphone and outputs a filtered signal, wherein the system subtracts the outputted filtered signal from a signal based on the microphone output signal to cancel noise and outputs the resulting signal, and the system further processes the resulting signal to obtain a further processed resulting signal to remove and/or eliminate residual feedback present in the resulting signal.