Directional Acoustic Filter for Noise Suppression
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Solution Overview
Problem
Existing noise suppression techniques for acoustic signals from multiple microphones face challenges in achieving high Signal-to-Noise Ratio (SNR) while minimizing artifacts, particularly when using a small number of microphones, due to limitations in directional analysis and noise estimation accuracy.
Innovation Solution
A directional acoustic filtering system that utilizes a filtration module with a directional analysis module to determine operative parameters for noise reduction, based on the sound field's directional characteristics, allowing for effective noise suppression and artifact minimization by distinguishing between direct and diffuse sounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex beam forming techniques are used to achieve high SNR and directional response, then noise suppression efficiency is improved, but device complexity and computational resources increase
Solution Approach 1:
The patent extracts only the essential directional information (direction of arrival and diffuseness) from the multi-microphone signals, rather than implementing full beam forming. This is achieved by computing directional parameters through statistical analysis of microphone signal correlations, which provides sufficient directional response and noise suppression without the computational burden of complete beam forming algorithms
Solution Approach 2:
The patent changes the approach from spatial filtering (beam forming) to parameter-based filtering. By computing direction of arrival and diffuseness parameters from microphone signals and using these parameters to control a single-microphone noise suppression filter, the system achieves beam forming-like performance with significantly reduced computational complexity
2Measurement precision
If more microphones are used to improve directional analysis accuracy, then noise estimation accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a minimal set of microphones (as few as two) to obtain sufficient directional information for effective noise suppression. Rather than requiring large microphone arrays for high precision directional analysis, the system computes directional parameters from limited microphone inputs using statistical methods, achieving adequate accuracy for practical noise suppression applications
Solution Approach 2:
The patent replaces the mechanical solution of using more microphones to improve directional accuracy with a computational approach. By using statistical analysis and parameter estimation algorithms on signals from fewer microphones, the system achieves comparable directional analysis accuracy without increasing the physical number of microphones
3Reliability
If aggressive noise reduction is applied to remove more noise, then noise suppression efficiency is improved, but artifacts in the output signal increase
Solution Approach 1:
The patent dynamically adjusts the noise suppression filter based on real-time estimation of noise diffuseness and direction of arrival. The filter characteristics change adaptively according to the spatial characteristics of the noise field, allowing aggressive noise reduction when noise is diffuse and background-like, while reducing suppression intensity when noise comes from specific directions or when speech is present, thereby minimizing artifacts
Solution Approach 2:
The system continuously estimates directional parameters (direction of arrival and diffuseness) from the microphone signals and uses this feedback to adjust the noise suppression filter in real-time. This closed-loop approach allows the system to optimize noise reduction while monitoring signal characteristics to avoid excessive suppression that would create artifacts
Data Source
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Figure 2A
AI summary
A system and method for use in filtering of an acoustic signal are provided for producing an output signal of attenuated amount of diffuse sound in accordance with predetermined parameters of desired output directional response and required attenuation of diffuse sound. The system includes a filtration module and a filter generation module including a directional analysis module and filter construction module.