Earpiece Audio Signal Gain Control Using Microphone Noise Estimation
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Solution Overview
Problem
Existing audio signal processing techniques for mobile communication devices are inefficient in enhancing earpiece audio quality on the near-end side, as they primarily focus on microphone signal processing at the far-end side and are complex and slow in adapting to changing noise conditions.
Innovation Solution
An audio signal processing apparatus and method that uses voice activity detection on the earpiece audio signal to determine a noise estimate from the microphone audio signal, allowing for adaptive enhancement of the earpiece audio signal by adjusting its gain based on noise levels, thereby improving voice intelligibility and mitigating near-end side noise effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive gain or equalization control techniques are applied on the near-end side, then the loudness of the earpiece audio signal is adjusted to avoid masking by local background noise, but the technique becomes complex and slow in adapting to changing noise magnitudes
Solution Approach 1:
The patent extracts the noise magnitude estimation function from the earpiece audio signal processing path and implements it separately using the microphone audio signal. This separation simplifies the overall system by dedicating specific processing to noise estimation, avoiding the complexity of analyzing the earpiece signal itself for noise characteristics.
Solution Approach 2:
The patent performs preliminary voice activity detection on the earpiece audio signal to determine when the far-end participant is speaking. This preliminary action enables the system to selectively apply noise magnitude estimation only during relevant periods, improving efficiency and reducing unnecessary processing complexity.
2Measurement precision
If complex voice activity detection on the microphone audio signal is used to estimate background noise magnitude, then noise estimation accuracy is improved, but the processing becomes slow and complex
Solution Approach 1:
The patent applies partial voice activity detection only on the earpiece audio signal rather than performing full complex VAD on the microphone signal. This partial action provides sufficient information to trigger noise estimation without requiring the excessive processing of complete spectral analysis, thus maintaining productivity while achieving adequate measurement precision.
3Reliability
If noise cancellation, noise suppression, or beam-forming techniques are applied at the far-end side, then the microphone signal quality is improved, but the enhancements are only noticed at the near-end side and no enhancements are noticed at the other side
Solution Approach 1:
The patent introduces an intermediary processing stage that uses the microphone audio signal to estimate noise magnitude, which then influences the processing of the earpiece audio signal. This intermediary approach allows enhancements to be applied locally at the near-end side based on noise conditions detected from the microphone, ensuring that benefits are perceived by the local user without requiring far-end processing.
Data Source
AI summary
The invention relates to an audio signal processing apparatus for processing an input earpiece audio signal upon the basis of a microphone audio signal, the audio signal processing apparatus comprising a voice activity detector being configured to determine a voice activity indicator signal upon the basis of the input earpiece audio signal, a noise magnitude determiner being configured to determine a microphone noise magnitude indicator signal upon the basis of the microphone audio signal, a gain factor determiner being configured to determine a gain factor signal upon the basis of the voice activity indicator signal and the microphone noise magnitude indicator signal, and a weighter being configured to weight the input earpiece audio signal by the gain factor signal to obtain an output earpiece audio signal.