Microphone Noise PSD Estimation for Automatic Vehicle Audio Gain Control
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Solution Overview
Problem
Variable acoustic noise in moving vehicles degrades the perceived quality of music or speech, requiring frequent adjustments in audio system volume, which can be inconvenient and lead to either inadequate or excessive volume levels.
Innovation Solution
A method and system that estimate the power spectral density of noise using a microphone signal, iteratively modifying the frequency domain representation to separate noise from audio sources, and generating a control signal to adjust acoustic transducer gains based on the noise estimate, thereby maintaining consistent audio quality across varying noise conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the volume of the audio system is increased to compensate for noise, then the audio quality is improved in noisy conditions, but the volume becomes too high when noise decreases, requiring manual adjustment
Solution Approach 1:
The system automatically monitors noise levels through microphone input and dynamically adjusts audio output levels without user intervention. The processing device continuously analyzes the acoustic environment and modifies the audio signal parameters in real-time, enabling the system to self-regulate and maintain optimal audio quality across varying noise conditions
Solution Approach 2:
The system uses a feedback mechanism where the microphone captures ambient noise, the processing device analyzes the noise characteristics, and the output is adjusted accordingly. This closed-loop control continuously adapts the audio system to current acoustic conditions, preventing both insufficient volume in noise and excessive volume when quiet
2Measurement precision
If traditional noise estimation methods are used, then computational resources are consumed, but frequency-specific noise information is not directly obtained
Solution Approach 1:
The system directly extracts frequency-specific noise information from the microphone signal by separating it from audio source contributions in the frequency domain. Instead of computing time-domain noise waveforms through complex processing, the method extracts the essential noise spectral characteristics directly, reducing computational overhead while maintaining measurement precision
Solution Approach 2:
The patent replaces traditional time-domain noise estimation mechanisms with a frequency-domain approach. By transforming the problem from time-domain signal processing to frequency-domain spectral analysis, the system achieves more efficient computation while obtaining direct frequency-specific noise information that can be immediately applied to audio adjustments
3Reliability
If multiple audio sources are present, then the audio system provides rich content, but separating noise from audio sources becomes more difficult
Solution Approach 1:
The system segments the audio signal into distinct frequency components and processes each frequency bin independently. By dividing the complex multi-source audio environment into separable frequency segments, the system can estimate noise characteristics for each segment without being overwhelmed by the complexity of multiple correlated sources, thereby maintaining noise separation accuracy while managing processing complexity
Data Source
AI summary
The technology described herein can be embodied in a method for estimating a power spectral density of noise, the method including receiving an input signal representing audio captured using a microphone. The input signal includes a first portion that represents acoustic outputs from two or more audio sources, and a second portion that represents a noise component. The method also includes iteratively modifying a frequency domain representation of the input signal, such that the modified frequency domain representation represents a portion of the input signal in which effects due to the first portion are substantially reduced. The method further includes determining, from the modified frequency domain representation, an estimate of a power spectral density of the noise, and generating a control signal configured to adjust one or more gains of an acoustic transducer. The control signal is generated based on the estimate of the power spectral density of the noise.