Hearing Instrument Echo Cancellation With Residual Echo Suppression
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Solution Overview
Problem
Hearing instruments used in conjunction with communication devices experience acoustic feedback, leading to echo issues during voice calls, which existing echo cancellation methods struggle to suppress effectively and efficiently.
Innovation Solution
A method involving an adaptive first filter to generate a compensation signal for echo reduction, followed by a second filter to suppress residual feedback, utilizing error and compensation signals to control the suppression process without additional computing power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive echo cancellation is implemented using existing methods, then some echo suppression is achieved, but the suppression is insufficient (echo remains audible) and computational resources are consumed
Solution Approach 1:
The echo cancellation process is divided into two independent stages: first, adaptive echo cancellation using the far-end signal to generate a compensation signal; second, residual echo suppression using a non-linear processor that operates on the error signal. This segmentation allows each stage to be optimized independently, achieving superior overall performance compared to single-stage approaches.
Solution Approach 2:
The error signal serves as an intermediary between the adaptive echo canceller and the residual echo suppressor. It carries the residual echo information that needs further suppression while being free from the strongly correlated far-end speech that would interfere with non-linear processing. This intermediary representation enables effective residual echo suppression without requiring additional far-end signal processing.
2Reliability
If multiple filter stages are added to improve echo suppression, then echo cancellation performance improves, but device complexity increases
Solution Approach 1:
The residual echo suppression function is merged with the existing adaptive echo cancellation structure by processing the error signal through a non-linear processor. This combines the linear adaptive filtering with non-linear residual suppression in an integrated manner, achieving enhanced echo cancellation without requiring completely separate parallel processing paths.
Solution Approach 2:
The system dynamically adapts its processing based on signal conditions. The adaptive filter continuously updates its coefficients based on error minimization, while the non-linear processor dynamically adjusts its gain based on the correlation between the error signal and far-end signal. This dynamic adaptation allows effective echo suppression across varying acoustic conditions without requiring complex fixed-structure multi-stage filters.
Data Source
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AI summary
The invention relates to a method for reducing echo in a hearing instrument (1), wherein a first input signal (x1) is generated from ambient sound (8) by an electroacoustic first input transducer (6) of the hearing instrument (1), wherein an external input signal (xe) is received from an external communication device (4) by means of a communication device (24) of the hearing instrument (1), wherein an output signal (y) is generated on the basis of the first input signal (x1) and the external input signal (xe) of the hearing instrument (1), wherein a compensation signal (c) for reducing echo and/or acoustic feedback (h) is generated on the basis of the output signal (y) in an adaptive first filter (18), wherein an error signal (e) is generated on the basis of the first input signal (x1) and the compensation signal (c).wherein a control variable (K) is generated based on filter coefficients of the first filter (18) and/or based on a comparison of the error signal (e) with the compensation signal (c) and/or with the first input signal (x1), wherein, depending on the control variable (K), a second filter (40) is applied to an intermediate signal (z) derived from the input signal (x1) to suppress a residual echo or residual feedback, thereby generating a transmission signal (t), and wherein the transmission signal (t) is transmitted to the external communication device (4) by means of the communication device (24).