Audio Signal Beamforming for Acoustic Echo Suppression
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Solution Overview
Problem
Acoustic echo and feedback in communication devices, such as TVs, remain significant issues due to high echo path gains and resonating frequencies, which can cause howling and interfere with communication, despite the use of microphone beamforming and placement strategies.
Innovation Solution
The method involves determining beamformer filter coefficients to apply destructive interference to audio signals output from speakers, using location information about the microphone relative to the speakers, including time delays, to suppress echo signals at the microphone, thereby reducing echo cancellation issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If microphones are placed as far away as possible from speakers to reduce acoustic echo, then the echo path gain is reduced, but resonating frequencies still cause high echo path gain and disturbance during calls
Solution Approach 1:
The patent converts the harmful resonating frequencies that cause echo into beneficial information by identifying these specific frequencies and using them as targets for selective suppression through adaptive filtering and beamforming techniques
Solution Approach 2:
The patent applies different processing strategies to different frequency components of the echo, specifically targeting resonating frequencies with adaptive filters while allowing other frequencies to pass through, rather than applying uniform echo cancellation across the entire frequency spectrum
2Object-affected harmful factors
If microphone beamforming is used to suppress echo from unwanted directions, then echo suppression is improved, but the number of microphones and array geometry limit the effectiveness, leaving echo audible
Solution Approach 1:
The patent combines multiple echo cancellation techniques including beamforming, adaptive filtering, and resonating frequency suppression into a unified processing system that leverages the strengths of each method to achieve superior echo cancellation
Solution Approach 2:
The patent dynamically adjusts beamforming weights and filter coefficients in real-time based on the identified resonating frequencies and current acoustic conditions, allowing the system to adapt to changing echo characteristics without requiring additional hardware
3Power
If both sides of a call use devices with high amplification in the echo path, then audio output is enhanced, but feedback or howling occurs due to mutual echo path amplification
Solution Approach 1:
The patent applies preliminary echo cancellation processing to the audio signal before it is amplified and output by the speakers, thereby preventing the echo from being amplified in the first place and eliminating the conditions that lead to feedback and howling
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 echo signals by exploiting destructive interference, improving communication quality by minimizing echo and feedback, even in environments with high echo path gains and resonating frequencies.
Implementation Method 1
determined such that the filtered audio signals destructively interfere with each other such that the filtered audio signals are suppressed when received at the microphone
Data Source
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AI summary
A method, device and computer program product for processing audio signals, the method comprising: determining beamformer filter coefficients to be applied to the audio signals; applying the beamformer filter coefficients to the audio signals; outputting the filtered audio signals from an audio output means comprising a plurality of speakers coupled with the device; and receiving at a microphone coupled with the device, the filtered audio signals output from the audio output means, wherein the filter coefficients are determined such that the filtered audio signals are suppressed when received at the microphone.