Microphone Echo Cancellation With Loudspeaker Delay Compensation
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Solution Overview
Problem
Existing audio capture systems face challenges in effectively reducing acoustic echoes in microphone signals, which degrade the quality of spatial audio in teleconferencing and mediated reality environments.
Innovation Solution
An apparatus and method that determine and apply specific delays to loudspeaker and microphone signals based on echo path delay estimates and time-frequency filterbanks to optimize echo cancellation, reducing processing latency and enhancing echo reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic echo cancellation filter uses future frames and time-frequency filterbank, then echo reduction quality is improved, but processing latency increases
Solution Approach 1:
The patent applies preliminary action by using future frames (look-ahead frames) in the time-frequency filterbank before the current frame is fully processed. This allows the echo cancellation filter to anticipate and cancel echo components that would otherwise appear in the output, improving echo reduction quality. The future frames are processed in advance and their results are used to adjust the current frame's echo cancellation, effectively performing the cancellation action before the echo would fully manifest.
Solution Approach 2:
The patent implements dynamics by dynamically adjusting delay values based on the echo path delay estimate and the number of future frames used. The delay compensation mechanism adapts in real-time to changing acoustic conditions and filter parameters, optimizing the balance between echo reduction quality and processing latency. The system dynamically selects the optimal number of future frames to use, adjusting the trade-off between quality improvement and latency introduction based on current operational requirements.
2Measurement precision
If echo path delay compensation is applied, then echo cancellation accuracy is improved, but system complexity increases
Solution Approach 1:
The patent applies parameter changes by adjusting delay values as configurable parameters in the echo cancellation system. The echo path delay estimate is used to modify the delay parameter applied to the loudspeaker signal, and the number of future frames modifies the delay applied to the microphone signal. These parameter adjustments improve echo cancellation accuracy by aligning the timing of reference and microphone signals, while keeping the implementation relatively simple through parameter tuning rather than structural complexity.
Solution Approach 2:
The system performs self-service by automatically estimating the echo path delay and using this estimate to configure the appropriate delay compensation. The echo cancellation filter self-adjusts its delay parameters based on the measured echo characteristics, reducing the need for manual configuration or complex external control systems. The system serves itself by using its own output (echo path estimate) to improve its input (delay compensation settings).
Data Source
AI summary
Apparatus, methods and computer programs are provided 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 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.