Vehicle Microphone Road Noise Cancellation Using Accelerometer Signals
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Solution Overview
Problem
Existing audio systems in vehicles suffer from road noise interference in microphone signals, degrading call quality in hands-free phone systems.
Innovation Solution
Utilizing accelerometer signals to estimate and subtract road noise components from microphone signals using adaptive and fixed filters, combined with echo cancellation and post-filtering techniques to enhance signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic echo cancellation (AEC) and noise suppression algorithms are used to improve voice call quality in moving vehicles, then speech intelligibility is improved, but road noise cancellation effectiveness deteriorates due to algorithm saturation and inability to distinguish road noise from other sounds
Solution Approach 1:
The patent segments the audio signal processing into distinct functional modules: a road noise canceller that specifically targets road noise using accelerometer data, and separate AEC and noise suppression algorithms that handle speech and other sounds. This segmentation allows each module to specialize in its specific task, preventing algorithm saturation and enabling effective road noise cancellation without compromising speech intelligibility.
Solution Approach 2:
The patent introduces accelerometer data as an intermediary element that provides independent road noise information to the road noise canceller. This intermediary data source enables the system to identify and cancel road noise without relying solely on the microphone signal, which is contaminated by both road noise and speech. The accelerometer acts as a mediator that bridges the gap between vehicle motion and noise cancellation.
2Measurement precision
If multiple microphones are used to capture speech signals, then speech capture quality is improved, but road noise contamination increases making it difficult to isolate speech from road noise
Solution Approach 1:
The patent extracts road noise information from accelerometer data and removes it from the microphone signals through dedicated road noise cancellation processing. By taking out the road noise component separately using the accelerometer as a reference, the system can then cleanly capture speech without road noise contamination, even when multiple microphones are used.
Solution Approach 2:
The patent applies different processing qualities to different signal components: road noise cancellation is applied specifically to the road noise frequency range using accelerometer correlation, while speech processing algorithms are applied to the speech frequency range. This local quality approach ensures that road noise is canceled without affecting speech quality, and vice versa.
Data Source
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AI summary
An audio system, including an accelerometer positioned to produce an accelerometer signal representative of road noise within a vehicle cabin; a microphone disposed within the vehicle cabin such that the microphone receives the road noise and produces a microphone signal having a road-noise component; and a road-noise canceler, comprising a road-noise cancellation filter, configured to receive the accelerometer signal and the microphone signal and to minimize the road-noise component of the microphone signal according to the accelerometer signal, to produce an estimated microphone signal.