Adaptive Cabin Noise Cancellation Using Chassis Vibration Sensing
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Solution Overview
Problem
Traditional hands-free telephony systems in vehicles struggle to suppress road noise without distorting speech, as existing signal processing methods often compromise audio quality.
Innovation Solution
An adaptive noise cancelling system utilizing multi-axis accelerometers and microphones to measure vehicle vibrations, generating a virtual microphone signal to subtract road noise via linear subtraction, employing algorithms like least mean squares filter to model transfer functions and cancel correlated noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional signal processing methods are used to suppress road noise, then road noise reduction is achieved, but speech quality is distorted
Solution Approach 1:
The system segments the noise cancellation task by using multiple accelerometers positioned at different locations (front, rear, left, right) to capture different components of road noise separately. Each accelerometer measures vibrations independently, allowing the system to process and cancel noise from different sources and directions independently, thereby reducing overall road noise without affecting speech quality
Solution Approach 2:
The system introduces accelerometers as intermediary devices that measure road noise vibrations independently from the speech signal. These accelerometers act as mediators by capturing only the noise components through vibration measurement, which are then subtracted from the microphone signal. This intermediary approach allows noise cancellation without directly processing and potentially distorting the speech signal
2Ease of operation
If microphones are used to capture speech in the vehicle cabin, then hands-free communication is enabled, but vehicular noise is picked up along with speech
Solution Approach 1:
The system extracts the road noise component from the combined speech and noise signal captured by microphones. By using accelerometers to separately measure road noise vibrations and then subtracting this extracted noise component from the microphone signal, the system removes vehicular noise while preserving the speech signal for hands-free communication
Solution Approach 2:
The system merges the output signals from multiple accelerometers with the microphone signal in a coordinated manner. The accelerometer data from different vehicle locations are combined to create a comprehensive road noise profile, which is then integrated with the speech signal processing to achieve effective noise cancellation while maintaining hands-free communication capability
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
Effectively reduces road noise by up to 13 dB in the voice band, preserving speech clarity and improving audio quality during hands-free calls.
Implementation Method 1
a plurality of multi-axis accelerometers mounted to the vehicle... pick up vibrations on a chassis of a vehicle
Implementation Method 2
the telephony noise canceller is configured to remove correlated road noise via linear subtraction
Implementation Method 3
the plurality of microphones is an array of microphones processed via a beamformer to generate a virtual microphone signal with road noise of the vehicle
Data Source
AI summary
An adaptive noise cancelling system utilizing a plurality of multi-axis accelerometers and a plurality of microphones, wherein the plurality of multi-axis accelerometers and the plurality microphones may be used in combination to pick up vibrations on a chassis of a vehicle. The accelerometers may be positioned at point near the suspension knuckles or joints of the vehicle, and the microphones may be positioned near the headrest and sun visor of the vehicle. The adaptive noise cancelling system may use an adaptive algorithm to derive one or more filter weights that model a transfer function between the vibrations on the chassis of the vehicle to an acoustic pressure at the plurality of microphones location.