Beamformer Initialization for Echo Suppression
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Solution Overview
Problem
In communication devices with both audio input and output means, echo signals from the output (such as loudspeakers) can interfere with audio inputs, and existing adaptive beamformers face challenges in quickly suppressing echoes without disrupting the beampattern, especially during the initial stages of communication events.
Innovation Solution
The method involves initializing the beamformer with an indication of the likely echo direction obtained from a data store, which is shared among similar devices, allowing for echo suppression before the first instance of far-end activity, and adapting coefficients if the actual echo direction differs, to minimize beampattern changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive beamformers are used to suppress echo signals, then echo suppression capability is improved, but the beampattern may be disrupted suddenly
Solution Approach 1:
The system performs preliminary action by initializing the beamformer with pre-determined beamformer coefficients before the communication event starts. These coefficients are calculated based on the known geometry between the loudspeaker and microphone array, allowing echo suppression to be activated immediately without sudden adaptation changes that would disrupt the beampattern.
2Reliability
If beamformer coefficients are adapted in real-time, then echo suppression is improved, but processing complexity increases
Solution Approach 1:
The complex task of determining optimal beamformer coefficients is performed in advance during system initialization, before the communication event begins. This preliminary calculation eliminates the need for real-time adaptation during active communication, reducing processing complexity while maintaining effective echo suppression.
Solution Approach 2:
The system uses self-service by automatically determining beamformer coefficients based on the known geometric relationship between the loudspeaker and microphone array. This self-determination eliminates the need for complex real-time analysis and external intervention, simplifying the processing requirements while achieving effective echo suppression.
3Object-affected harmful factors
If echo suppression is applied immediately, then echo interference is reduced, but audio quality from desired directions may be degraded
Solution Approach 1:
The beamformer applies local quality by using direction-dependent gain values that are specifically designed to suppress echoes from the loudspeaker direction while preserving audio signals from desired communication directions. The pre-determined beamformer coefficients encode this directional differentiation, allowing selective suppression without degrading desired audio quality.
Data Source
AI summary
Audio signals are processed for use in a communication event. A data store may be queried to obtain an indication of an echo direction, which relates to a direction from which audio signals output from the audio output are likely to be received at a microphone array (plurality of microphones) of a device. Beamformer coefficients of an adaptive beamformer of the device are determined in dependence upon the received indication of the echo direction. Audio signals are received at the microphone array. The adaptive beamformer applies the determined beamformer coefficients to the received audio signals, thereby generating a beamformer output for use in the communication event. The beamformer coefficients are determined such that echo suppression is applied to audio signals received at the microphone array from the indicated echo direction.