Wind Noise Suppression Using Spatially Separated Microphones
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Solution Overview
Problem
Wind noise, being impulsive and non-stationary, degrades the quality and intelligibility of speech signals picked up by microphones, as conventional noise suppression methods fail to effectively attenuate it due to its bursty nature and local occurrence.
Innovation Solution
A multi-microphone system with spatially separated primary and reference microphones detects and suppresses wind noise by utilizing differences in signal magnitude and energy between the two microphones, employing time-varying blocking matrices and active noise cancellers to isolate and remove wind noise before acoustic noise suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional noise suppression schemes are used, then acoustic noise and system-introduced noise are suppressed, but wind noise is not attenuated due to its non-stationary and impulsive nature
Solution Approach 1:
The patent segments the noise suppression task by separating wind noise detection and suppression from conventional acoustic noise suppression. It uses a dedicated wind noise detector that analyzes signal characteristics independently from standard noise suppression algorithms, allowing specialized handling of impulsive wind noise while maintaining conventional noise suppression for other noise types.
Solution Approach 2:
The patent changes detection parameters by monitoring signal energy, autocorrelation values, and spectral characteristics dynamically. The wind noise detector adjusts its detection thresholds and parameters based on the non-stationary nature of wind noise, enabling effective detection of impulsive wind noise that conventional stationary noise suppression methods cannot handle.
2Measurement precision
If multiple microphones are used with spatial separation, then wind noise detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent introduces a reference microphone as an intermediary element that captures environmental noise including wind noise without capturing the speech signal. This reference microphone serves as a mediator that provides a wind noise reference signal, which is then used by the wind noise detector to identify and suppress wind noise in the primary microphone signal without requiring complex multi-microphone arrays.
Solution Approach 2:
The patent extracts the wind noise component by separating it from the speech signal using the reference microphone. The wind noise detector extracts wind noise characteristics from the reference signal and uses them to identify and remove wind noise from the primary speech signal, effectively isolating the harmful wind noise component for targeted suppression.
3Object-affected harmful factors
If wind noise suppression is applied aggressively, then wind noise attenuation is improved, but speech signal quality and intelligibility are degraded
Solution Approach 1:
The patent applies partial suppression by using a suppression gain that varies dynamically based on wind noise detection confidence and signal characteristics. Instead of uniformly suppressing all detected wind noise, the system applies suppression only when and where wind noise is confidently detected, using partial suppression gains that maintain speech quality while reducing wind noise impact.
Solution Approach 2:
The patent implements feedback mechanisms where the wind noise detector continuously monitors the suppressed signal and adjusts suppression parameters in real-time. The system uses feedback from signal energy analysis, autocorrelation measurements, and spectral characteristics to dynamically adjust suppression strength, preventing over-suppression that would degrade speech quality while maintaining effective wind noise reduction.
Data Source
AI summary
Unlike sound based pressure waves that go everywhere, air turbulence caused by wind is usually a fairly local event. Therefore, in a system that utilizes two or more spatially separated microphones to pick up sound signals (e.g., speech), wind noise picked up by one of the microphones often will not be picked up (or at least not to the same extent) by the other microphone(s). Embodiments of methods and apparatuses that utilize this tact and others to effectively detect and suppress wind noise using multiple microphones that are spatially separated are described.