Clip Compensation Accuracy in Multi-Microphone Echo Cancellation
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Solution Overview
Problem
In smart speakers and similar devices, the echo cancellation process often reduces the accuracy of clip compensation for signals from multiple microphones, making it difficult to separate output signal components and target sounds, which affects speech direction estimation and voice recognition.
Innovation Solution
A signal processing device with an echo cancellation unit, a clip detection unit, and a clip compensation unit that performs compensation after the echo cancellation process, using an average power ratio between non-clipped and clipped microphones to suppress the signal of the clipped microphone, adjusting the suppression amount based on speech levels and voice recognition characteristics, and optionally adjusting the positions of microphones or the speaker to minimize clipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If clip compensation is performed on a signal before the echo cancellation process, then the processing flow is simpler, but the clip compensation accuracy decreases because the output signal component of the speaker and target sound are difficult to separate
Solution Approach 1:
The patent applies preliminary action by performing echo cancellation before clip compensation. The echo cancellation unit removes the speaker output signal component from the microphone signals in advance, creating a cleaned signal that is then used for clip compensation. This preliminary removal of the interfering echo signal enables accurate clip compensation by allowing the target sound to be processed without the masking effect of the speaker output, thereby resolving the contradiction between processing simplicity and compensation accuracy.
2Volume of moving object
If the positions of microphones are closer to the speaker for device design, then the device structure is more compact, but clipping occurs more frequently during loud sound reproduction
Solution Approach 1:
The patent converts the harmful effect of clipping into a beneficial outcome by detecting clipped portions in the microphone signals and compensating for them using information from non-clipped time periods. The clip detection unit identifies when clipping occurs, and the clip compensation unit uses the transfer characteristic estimated during non-clipped periods to reconstruct the original signal values during clipped periods. This transforms the previously harmful clipping distortion into an opportunity to demonstrate the robustness of the echo cancellation and clip compensation system, thereby resolving the contradiction between compact device design and signal reliability.
Data Source
AI summary
Compensation accuracy is increased with respect to clip compensation in a case where signals from a plurality of microphones are subjected to an echo cancellation process.A signal processing device according to an embodiment of the present technology includes an echo cancellation unit that performs an echo cancellation process of canceling an output signal component from a speaker on signals from a plurality of microphones, a clip detection unit that performs a clip detection for signals from the plurality of microphones, and a clip compensation unit that compensates for a signal after the echo cancellation process of clipped one of the microphones on the basis of a signal of non-clipped one of the microphones.