Adaptive Noise Suppression for Compact Microphone Arrays
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Solution Overview
Problem
Conventional noise suppression technologies using microphone arrays face challenges with limited placement positions, leading to reduced noise suppression effectiveness and signal distortion due to inter-microphone distance constraints, especially in smaller devices like mobile phones.
Innovation Solution
A noise suppression device that computes a phase difference utilization range and amplitude conditions based on inter-microphone distance and sampling frequency to determine suppression coefficients, allowing for effective noise suppression without phase rotation and distortion, even in constrained microphone array placements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inter-microphone distance is increased to improve noise suppression effectiveness, then the noise suppression amount increases, but the device size increases and placement flexibility decreases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the phase difference utilization range based on the actual inter-microphone distance. By computing the optimal frequency band for phase difference utilization according to the specific device configuration, the system achieves effective noise suppression adapted to each device's physical constraints without requiring a fixed large microphone separation
Solution Approach 2:
The system implements dynamics by making the noise suppression parameters adaptive rather than fixed. The phase difference utilization range is computed and adjusted based on the actual inter-microphone distance and sampling frequency, allowing the noise suppression effectiveness to be optimized for each specific device configuration and placement scenario
2Reliability
If the inter-microphone distance is increased to improve noise suppression amount, then the noise suppression effectiveness improves, but signal distortion increases due to phase rotation
Solution Approach 1:
The patent resolves this contradiction by dynamically changing the phase difference utilization range parameter based on the inter-microphone distance. By computing the optimal frequency band where phase rotation does not occur for the given microphone separation, the system achieves effective noise suppression while avoiding signal distortion in the selected frequency range
Solution Approach 2:
The system applies local quality by selectively applying phase difference-based noise suppression only to the computed utilization range where it is effective and distortion-free. Frequencies outside this range are handled differently, ensuring that noise suppression is applied locally where it provides benefit without causing harmful phase rotation effects
3Volume of moving object
If the microphone array placement is constrained to maintain small device size, then the device portability improves, but noise suppression precision decreases
Solution Approach 1:
The patent resolves this contradiction by computing the phase difference utilization range based on the actual small inter-microphone distance and sampling frequency. This adaptive parameter adjustment allows the system to maximize noise suppression precision within the constraints of small device size by optimizing the frequency band utilization for the given physical configuration
Solution Approach 2:
The system implements dynamics by making the noise suppression algorithm adaptive to the specific microphone array configuration. Rather than requiring fixed optimal placements, the system dynamically computes the utilization range based on the actual distances and sampling parameters, allowing effective noise suppression in compact device configurations
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
Enables appropriate noise suppression with low audio distortion by utilizing phase and amplitude differences within computed frequency bands, enhancing noise suppression precision and flexibility in microphone array placement limitations.
Implementation Method 1
a phase difference computation section that computes phase differences between the respective input sound signals
Implementation Method 2
an amplitude ratio computation section that computes amplitude ratios for respective frequencies between the input sound signals
Data Source
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AI summary
A noise suppression device includes a phase difference derived suppression coefficient computation section that over a phase difference utilization range computes for each frequency a phase difference derived suppression coefficient based on a phase difference, an amplitude ratio derived suppression coefficient computation section that computes for each frequency an amplitude ratio derived suppression coefficient based on an amplitude ratio or an amplitude difference, and based on the amplitude conditions, and a suppression section that suppresses noise contained in the input sound signals based on a suppression coefficient determined by using the phase difference derived suppression coefficient and the amplitude ratio derived suppression coefficient.