Microphone Reference Switching for Echo and Wind Noise
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Solution Overview
Problem
Electronic devices face challenges in accurately detecting and processing speech due to interference from wind noise and playback audio, which can distort audio signals and hinder effective voice command recognition.
Innovation Solution
The device employs beamforming techniques using both fixed and adaptive beamformers to isolate desired audio, combined with adaptive interference cancellation (AIC) and acoustic echo cancellation (AEC) to suppress noise, particularly when playback audio data is unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If acoustic echo cancellation (AEC) is used to remove playback audio from microphone signals, then playback interference is reduced, but the system cannot effectively suppress wind noise when playback audio data is unavailable
Solution Approach 1:
The patent introduces a reference signal as an intermediary element that enables adaptive interference cancellation. This reference signal serves as a mediator between the playback audio source and the microphone signals, allowing the system to cancel both playback interference and wind noise effectively. The reference signal acts as a common denominator that correlates with both types of noise, enabling unified suppression through adaptive filtering.
Solution Approach 2:
The patent implements dynamic adaptation of filter coefficients based on real-time analysis of microphone signals and reference signals. The system continuously updates its cancellation parameters to adapt to changing acoustic conditions, whether playback audio is present or absent. This dynamic behavior allows the system to effectively suppress different types of noise (playback interference when audio is playing, wind noise when it is not) by adjusting its cancellation strategy in response to environmental changes.
2Measurement precision
If beamforming techniques are used to isolate desired audio, then speech detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent divides the audio signal processing into distinct segments: beamforming stage, adaptive interference cancellation stage, and speech detection stage. Each segment handles specific aspects of signal processing independently, allowing for optimized processing at each stage. The beamforming segment isolates spatial information, the AIC segment removes interference based on reference signals, and the detection segment focuses on speech recognition, reducing overall system complexity through functional decomposition.
Solution Approach 2:
The patent employs adaptive interference cancellation as a universal solution that handles multiple types of interference (playback audio and wind noise) through a single unified process. The same adaptive filtering mechanism and reference signal approach work for both interference types, eliminating the need for separate specialized processors for each noise type and thereby reducing device complexity while maintaining speech detection accuracy.
Data Source
AI summary
Techniques for improving microphone noise suppression are provided. When a playback signal is available, a device may use the playback signal as a reference while performing Acoustic Echo Cancellation (AEC) processing. When the playback signal is not available, the device may instead use microphone audio signal(s) as the reference while performing Adaptive Interference Cancellation (AIC) processing. For example, the device may use first audio data generated by first microphones as the reference while performing AIC processing on the first audio data and second audio data generated by second microphones. As the adaptive filter used to perform AIC processing is updated at a slower rate, the reference signal only cancels stationary portions of the first audio data (e.g., noise), leaving a representation of transient sounds such as speech. In some examples, the device may perform AIC processing and AEC processing in series.