Acoustic Echo Cancellation Delay Alignment for Low-Latency Audio
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Solution Overview
Problem
Existing audio capture systems suffer from acoustic echoes that degrade the quality of spatial audio captured by microphones, particularly in teleconferencing and mediated reality environments, due to the echo path impulse response and processing delays.
Innovation Solution
Implementing an acoustic echo cancellation filter that accounts for the echo path impulse response by adding delays to both the loudspeaker and microphone signals, optimizing the filter parameters and time shifts to minimize echo and processing latency, using a combination of time-frequency filterbanks and sub-band adaptive filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If acoustic echo cancellation is applied using traditional filters, then echo reduction is achieved, but processing latency increases and quality of experience deteriorates
Solution Approach 1:
The patent segments the audio signal processing into multiple frequency bands using filterbanks. Each band is processed independently with tailored echo cancellation parameters, allowing optimized processing latency for each frequency range while maintaining overall echo reduction effectiveness.
Solution Approach 2:
The patent implements dynamic adaptation of echo cancellation filter parameters based on real-time analysis of the acoustic environment. The system continuously adjusts filter coefficients, delay values, and processing intensity to match changing conditions, minimizing processing latency while maintaining echo cancellation performance.
2Object-affected harmful factors
If echo cancellation filtering is applied, then echo return loss is improved, but device complexity increases
Solution Approach 1:
The patent divides the complex echo cancellation task into multiple simpler sub-tasks by segmenting the frequency spectrum. Each frequency band is handled by a dedicated, simplified filter structure, reducing the computational complexity of each individual processing unit while achieving superior overall echo return loss through coordinated multi-band processing.
Data Source
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AI summary
Examples of the disclosure relate to apparatus, methods and computer programs for reducing echo in microphone signals. The apparatus can be configured to obtain an echo path delay estimate and obtain information indicative of a number of future frames used by an acoustic echo cancellation filter. The acoustic echo cancellation filter comprises a time-frequency filterbank configured to generate an acoustic echo cancelled signal for a current time frame. The apparatus can also be configured to obtain information indicative of a time shift between consecutive frames processed by the acoustic echo cancellation filter. The apparatus can also be configured to determine at least a first delay to be added to a loudspeaker signal and determine at least a second delay to be added to a microphone signal. The determination of the first delay and the second delay is based on the echo path delay estimate, the number of future frames and the time shift between consecutive frames processed by the acoustic echo cancellation filter. The first delay and the second delay are determined so that an effective echo path delay is obtained that is dependent upon the time shift.