Coherence Processing for Vehicle Noise Estimation
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Solution Overview
Problem
Modern audio reproduction systems in vehicles face challenges with dynamic sound adjustment due to the complexity and cost associated with multichannel adaptive filtering, particularly in handling non-linear processing and high channel counts, which leads to difficulties in accurately separating noise from audio signals.
Innovation Solution
The system employs coherence processing between two microphones to estimate noise levels, reducing the need for multiple adaptive filters and accommodating various input sources like 5.1-channel surround sound, while effectively handling non-linear signals by determining the coherence between microphone signals to adjust audio output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multichannel adaptive filtering is used for noise separation, then noise separation accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts only the necessary information from microphone signals by computing coherence between pairs of microphones at specific frequency bands, rather than implementing full multichannel adaptive filtering. This selective extraction of coherence information achieves noise separation without requiring complex multichannel processing structures.
Solution Approach 2:
The patent uses coherence computation as a simplified copy or approximation of full multichannel adaptive filtering. By computing coherence between microphone pairs, the system obtains noise separation capability that mimics the效果 of complex adaptive filtering but with significantly reduced computational requirements and system complexity.
2Measurement precision
If multichannel adaptive filtering is used for noise separation, then noise separation accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive multichannel adaptive filtering hardware with a simpler, more cost-effective coherence computation approach. The system uses basic microphone elements and processes their signals through coherence calculation, which requires less sophisticated and therefore less expensive hardware infrastructure.
3Adaptability or versatility
If multiple adaptive filters are used for high channel counts, then handling of various input sources is improved, but device complexity increases
Solution Approach 1:
The coherence-based noise estimation system serves as a universal solution that handles multiple input source configurations (stereo, 5.1 surround, high channel counts) through a single coherent approach. Rather than implementing separate adaptive filters for each channel configuration, the system universally applies coherence computation between microphone pairs, which adapts to any input source type.
4Device complexity
If coherence processing is used instead of multichannel adaptive filtering, then device complexity is reduced, but noise separation accuracy may be compromised
Solution Approach 1:
The patent focuses coherence computation on specific frequency bands (particularly high-frequency bands above 4 kHz where noise is predominant) rather than processing the entire frequency spectrum. This selective parameter approach concentrates computational resources on the most noise-prone frequencies, achieving effective noise separation with reduced overall system complexity.
Data Source
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AI summary
A system that performs noise estimation for an audio adjustment application comprises a coherence calculator that determines at least one coherence value between microphone signals generated by at least two microphones that each independently senses acoustic energy in a listening space. A first microphone of the at least two microphones generates a first microphone signal from the acoustic energy and a second microphone of the at least two microphones generates a second microphone signal from the acoustic energy. The acoustic energy comprises a combination of an audio signal transduced by one or more speakers and environmental noise of the acoustic energy that is local to the listening space. A noise estimate computation processor determines an estimate of a level of the environmental noise based on the at least one coherence value.