Vehicle Voice Audio Filtering for Feedback and Noise Suppression
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Solution Overview
Problem
Existing voice-enhancement systems in motor vehicles face challenges with background noise interference, particularly in vehicles where engine noise masks voice commands, and feedback suppression is inadequate, leading to overmodulation issues.
Innovation Solution
A method and device utilizing a bandpass filter between the microphone and loudspeaker, where the filter is adjusted based on the power of the signal as a function of frequency, using derivatives to identify local maxima and adjust the filter to block feedback frequencies, thereby reducing background noise and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bandpass filter is adjusted based on signal power and frequency derivatives to block feedback frequencies, then feedback suppression and background noise filtering are improved, but device complexity increases
Solution Approach 1:
The system performs preliminary analysis of the signal power spectrum and its derivatives before adjusting the bandpass filter parameters. By calculating the first derivative of signal power with respect to frequency and identifying local maxima in advance, the system proactively configures the filter to prevent feedback issues rather than reacting to them after they occur.
Solution Approach 2:
The system continuously monitors the signal power as a function of frequency and uses this feedback information to dynamically adjust the bandpass filter parameters. The derivative of the power signal provides feedback about frequency trends, enabling the filter to adapt to changing acoustic conditions and maintain optimal feedback suppression.
2Measurement precision
If multiple microphones are used to capture voice signals, then voice recognition accuracy is improved, but feedback and overmodulation issues worsen
Solution Approach 1:
The bandpass filter acts as an intermediary element between the microphones and the voice recognition system. By strategically positioning the filter in the signal path and adjusting its parameters based on frequency analysis, it mediates the interaction between multiple microphone inputs and the processing system, preventing feedback while preserving voice signal integrity.
3Loss of information
If the bandpass filter is dynamically adjusted based on signal power derivatives, then voice command clarity is improved, but processing time and computational load increase
Solution Approach 1:
The system calculates the first derivative of the power signal with respect to frequency to identify trends, but focuses computational effort on detecting local maxima rather than performing exhaustive analysis across the entire frequency spectrum. This partial action approach provides sufficient information for effective filter adjustment without the excessive computational burden of complete spectral analysis.
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
Improves verbal communication in vehicles by effectively filtering out background noise and suppressing feedback, enhancing the clarity of voice commands and reducing overmodulation.
Implementation Method 1
Everywhere that microphones and loudspeakers are placed in an acoustically coupleable vicinity, the acoustic signal that is extracted, coupled out or decoupled at the loudspeaker is fed back into the microphone. The result is a so-called feedback
Data Source
AI summary
In a method and equipment for operating a voice-supported system, such as a communications and/or intercom/two-way intercom device in a motor vehicle, using at least one microphone and at least one loudspeaker to reproduce a signal generated by the microphone, as well as a bandpass filter configured between the microphone and the loudspeaker, a power of the signal as a function of a frequency is determined, and the bandpass filter is adjusted as a function of at least one local maximum of the power of the signal as a function of the frequency.