Adaptive Noise Suppression Using Reference Signal Filtering
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Solution Overview
Problem
Current audio signal processing technologies lack effective methods to suppress mechanical noise disturbances in microphones, particularly in scenarios where the noise is not related to known stimuli, leading to interference with desired audio signals during audio conferencing.
Innovation Solution
A method and system that utilize an adaptive filter to suppress noise by processing a reference signal separate from the audio signal, classifying potential noise events, and applying a control signal to modify the audio signal in the frequency domain, thereby reducing noise while minimizing impact on the desired signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a microphone is positioned close to the device to capture audio, then the desired acoustic signal can be captured, but mechanical disturbances from user interface operations and physical manipulation create loud nuisance audio signals that interfere with the desired signal
Solution Approach 1:
The system separates the audio processing into two independent channels: a primary microphone for desired audio capture and a secondary reference microphone for nuisance noise detection. This segmentation allows the system to identify and suppress mechanical disturbance noise without affecting the desired audio signal from the primary microphone.
Solution Approach 2:
A reference microphone acts as an intermediary sensor that detects mechanical disturbance noise separately from the desired audio signal. The noise from this reference channel is then processed and subtracted from the primary audio signal, effectively removing the nuisance noise while preserving the desired audio content.
2Object-affected harmful factors
If traditional noise suppression techniques are applied to suppress nuisance audio, then mechanical noise can be reduced, but the desired audio signal may also be attenuated or distorted
Solution Approach 1:
The system uses adaptive filtering with continuous feedback from the reference microphone to dynamically adjust noise suppression. The filtered xLMS algorithm continuously adapts the filter coefficients based on the correlation between the reference noise signal and the primary audio signal, ensuring that only nuisance noise is suppressed while preserving the desired audio signal integrity.
Solution Approach 2:
The system dynamically changes the filter parameters (coefficients) in real-time based on the characteristics of the detected noise and desired signal. This adaptive parameter adjustment allows the system to optimize noise suppression for different acoustic environments and disturbance types without compromising the desired signal.
3Device complexity
If a single microphone module is used without reference signal processing, then the device complexity is low, but effective noise suppression cannot be achieved for independent mechanical disturbances
Solution Approach 1:
The reference microphone serves multiple functions: detecting mechanical disturbance noise, providing a reference signal for adaptive filtering, and enabling the system to handle various types of nuisance audio from different sources. This multi-functionality is achieved with minimal additional hardware complexity.
Solution Approach 2:
The system replaces complex mechanical noise isolation structures with signal processing-based noise suppression. Instead of using physical barriers or specialized microphone placements to avoid mechanical noise, the system uses digital signal processing to identify and remove the noise components from the audio signal.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively suppresses mechanical noise disturbances, improving audio quality by selectively attenuating noise events while maintaining the desired audio signal integrity, even in proximity to noise sources.
Implementation Method 1
applying an adaptive filter to a sliding temporal window of the control signal in the frequency domain
Data Source
AI summary
Described herein is a method and audio capture system for suppressing noise due to mechanical disturbances in an audio capture system. In one embodiment a method includes the steps of: a) receiving an input audio signal from a microphone; b) receiving an input reference signal separate from the input audio signal; c) processing the input reference signal to generate a control signal for identifying a noise event; d) in response to the control signal, estimating a contribution of the noise event to the input audio signal by applying an adaptive filter to a sliding temporal window of the control signal in the frequency domain; and e) based on the estimated contribution, selectively modifying the input audio signal to generate an output audio signal in which the noise arising from the noise event is at least partially suppressed.