Vehicle Audio Delay Compensation Using Cross-Correlation
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Solution Overview
Problem
In vehicle cabins, combining audio signals from multiple microphones can result in unwanted noise due to differences in sound reception, leading to a less clear output through the audio system, as the sound received at one microphone may differ from that received at another, often accompanied by background noise.
Innovation Solution
The method involves receiving audio streams at multiple microphones, converting them into digital time series, calculating the delay between these streams using cross-correlation techniques, and processing the audio using the calculated delay to remove unwanted noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If audio signals from multiple microphones are combined, then the audio system can receive responses from vehicle occupants more comprehensively, but unwanted noise is introduced due to differences in sound reception at different microphone locations
Solution Approach 1:
The system performs preliminary actions by calculating the delay between microphone signals in advance, before combining the audio streams. The processor determines the time difference of arrival between signals at different microphones and pre-processes them by applying delay compensation, ensuring that signals are temporally aligned before summation. This prevents noise cancellation issues that would occur if signals with different delays were directly combined.
Solution Approach 2:
The system changes the temporal parameter of the audio signals by applying delay compensation. The processor adjusts the timing of signals from different microphones based on calculated delay values, transforming the parameter structure of the combined audio stream. This parameter transformation allows signals from multiple microphones to be coherent when combined, reducing unwanted noise while maintaining comprehensive audio coverage.
2Measurement precision
If multiple microphones are used to capture audio throughout the vehicle cabin, then speech detection capability is improved, but the processing complexity increases due to the need to reconcile signal differences
Solution Approach 1:
The system performs preliminary delay calculation using cross-correlation analysis before the main audio processing task. By determining the time delay between microphone signals in advance and storing these delay values for reuse, the system avoids repeated complex calculations during real-time speech detection, thereby reducing processing complexity while maintaining high speech detection accuracy.
Solution Approach 2:
The system creates a simplified representation of the acoustic environment by calculating and storing delay parameters that characterize the spatial relationships between microphones and sound sources. These delay copies are then applied to incoming audio streams, allowing the complex multi-microphone processing to be reduced to simpler operations using pre-computed parameters, thus reducing real-time processing complexity.
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
This approach effectively removes noise and improves audio quality by accurately determining the time lag between audio streams, enhancing the clarity of the output through the audio system.
Implementation Method 1
calculating a delay that exists between the first audio stream and the second audio stream based on a cross-correlation of the first digital time series and the second digital time series
Data Source
AI summary
A method of processing audio received at a plurality of microphones in a vehicle includes receiving the audio as a first audio stream and second audio stream at respective first and second microphones that are positioned at different locations within the vehicle; creating a first digital time series and a second digital time series that represent the first audio stream and the second audio stream, respectively; calculating a delay that exists between the first audio stream and the second audio stream based on a cross-correlation of the first digital time series and the second digital time series; and processing the received audio using the calculated delay.