Wearable Audio Crosstalk Noise Reduction via Accelerometer Signal Processing
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Solution Overview
Problem
Wearable audio devices, such as hearing aids and earphones, face challenges in reducing crosstalk noise from the output speaker to the accelerometer, which interferes with voice detection, and in alleviating the discomfort caused by occluding the ear canal, which blocks both external sounds and tissue-conducted signals.
Innovation Solution
A method that determines a crosstalk transfer function to subtract crosstalk signals from the accelerometer signal, and actively presents the inverted tissue-conducted speech signal to reduce occlusion perception by combining it with the input audio signal, while dynamically adjusting the contribution of accelerometer and microphone signals based on noise conditions to enhance speech intelligibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the output speaker transmits vibrations via mechanical parts to the accelerometer, then the accelerometer can detect tissue-conducted speech signals, but the accelerometer signal becomes corrupted by crosstalk from the output speaker
Solution Approach 1:
A crosstalk transfer function is introduced as an intermediary mathematical model that characterizes the vibration transmission path from the output speaker to the accelerometer. This transfer function enables the system to separate the desired tissue-conducted speech signal from the harmful crosstalk signal by modeling and subtracting the crosstalk component based on the speaker signal and transfer function characteristics.
Solution Approach 2:
The patent replaces direct mechanical isolation (which would prevent vibration detection) with a signal processing approach. Instead of physically preventing the speaker from vibrating the accelerometer housing, the system uses digital signal processing to subtract the predicted crosstalk signal from the accelerometer output, thereby eliminating the harmful mechanical coupling effect through computational means.
2Reliability
If the wearable audio device occludes the ear canal, then external sounds and tissue-conducted signals are blocked, but this causes discomfort to the user
Solution Approach 1:
The patent converts the harmful occlusion effect into a beneficial feature by actively detecting tissue-conducted speech signals through the accelerometer and presenting these signals back to the user via the output speaker. This creates an acoustic feedback loop that compensates for the ear canal occlusion, allowing users to still perceive their own voice and external sounds despite the physical blockage, thereby eliminating discomfort while maintaining signal transmission reliability.
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 crosstalk noise and alleviates the discomfort of occlusion by accurately isolating and presenting tissue-conducted speech signals, improving speech intelligibility and user experience by minimizing unwanted noise and perceived occlusion.
Implementation Method 1
The tissue conduction can include bone conduction and/or soft tissue conduction. Herein, the term accelerometer is used to refer to any inertial sensor configured to detect vibration of the user's vocal chords, mouth or throat, based on vibrations in bones and tissue of the user's head.
Implementation Method 2
sensing the vibrations that the voice transmits through the user's body, predominantly through the skull, to the housing or other mechanical part of a wearable audio device
Implementation Method 3
determining a characteristic crosstalk transfer function for audio signals being transferred from the output speaker to the accelerometer
Data Source
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AI summary
The disclosure relates to a method of processing an audio signal in a wearable audio device. The method comprises recording a microphone signal with one or more microphones of the audio device, and further recording an accelerometer signal with one or more accelerometers of the audio device indicative of an acceleration of the audio device with respect to one or more axes; and determining an output audio signal based on the microphone signal(s) and the accelerometer signal(s).