Adaptive Audio Noise Compensation for Stable In-Car Sound
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio systems in vehicles struggle to effectively compensate for ambient noise, leading to instability and undesirable gain changes due to limited bandwidth and lack of consideration for spectral distribution of noise signals, resulting in suboptimal sound reproduction.
Innovation Solution
An adaptive system that extracts ambient noise using an adaptive filter with a variable step size, generates a control signal to adjust audio output, and incorporates a whitening filter for spectral smoothing, along with a voice activity detection model to manage noise and voice signals, enhancing sound quality by considering the noise level and spectral distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an adaptive filter with fixed step size is used to extract noise signals, then the system can operate with simpler control logic, but the system becomes unstable and produces undesirable gain changes when noise levels vary dynamically
Solution Approach 1:
The patent applies dynamics by making the adaptive filter's step size variable rather than fixed. The step size controller dynamically adjusts the step size parameter based on current operating conditions, allowing the filter to adapt its convergence speed and stability characteristics to match the instantaneous noise environment, thereby resolving the contradiction between simple control logic and system stability.
Solution Approach 2:
The patent changes the parameter of the adaptive filter from a fixed step size to a variable step size that is continuously adjusted by the step size controller. This parameter change allows the system to optimize its performance by modifying the adaptation rate according to noise characteristics, achieving both stability and responsiveness without excessive complexity.
2Adaptability or versatility
If the adaptive filter operates with broadband signals, then the system can process all frequency components, but the desired music signal penetrates through the filter causing gain chase situations
Solution Approach 1:
The patent applies local quality by making the noise extraction filter's characteristics frequency-dependent. Rather than applying a uniform filtering approach across all frequencies, the system allows different frequency components to be processed with appropriate filtering strength, preventing music signal penetration in critical frequency ranges while maintaining noise extraction capability where needed.
3Device complexity
If the system uses strongly undersampled signals to reduce implementation complexity, then the system becomes easier to implement, but the control signal is derived solely from low-frequency noise components
Solution Approach 1:
The patent substitutes the mechanical sampling approach with a signal processing solution. Instead of increasing the sampling rate to capture all noise components (which would increase implementation complexity), the system uses a whitening filter to process the undersampled signal, transforming the correlated noise components into uncorrelated ones that can be accurately represented at lower sampling rates.
4Device complexity
If the VAD operates continuously in the time range with fixed increments and decrements, then the voice detection is simple to implement, but the control signal is delayed and only reaches a stationary final value
Solution Approach 1:
The patent applies periodic action by using frame-based processing with overlapping windows. Instead of continuous fixed-increment adjustment, the system processes the signal in periodic frames, allowing for more sophisticated noise estimation and reduction algorithms to be applied without excessive computational complexity, thereby reducing control signal delay while maintaining implementability.
Data Source
AI summary
A system is provided for enhancing a sound signal produced by an audio system in a listening environment by compensating for ambient noise in the listening environment. The system receives an electrical sound signal and generates a sound output therefrom. A total sound signal is sensed representative of the total sound level in the environment, where the total sound level includes the sound output and the ambient noise. The system extracts an ambient noise signal representative of the ambient noise from the total sound signal, using an adaptive filter with an adaptive step size, in response to the total sound signal and to a reference signal derived from the electrical sound signal. The system generates a control signal in response to the ambient noise signal and adjusts the sound output of the audio system to compensate for the ambient noise level in response to the control signal.