Virtual Microphone Noise Cancellation in Vehicle Cabin
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Solution Overview
Problem
Existing active noise control systems in vehicles are limited in effectively canceling noise at specific locations within the cabin, particularly due to the need for multiple noise-cancelling microphones placed close to occupants' ears, which can be aesthetically and cost-inefficient.
Innovation Solution
The implementation of a method and system that estimates noise at virtual locations using a processor, microphone, and loudspeaker, utilizing transfer functions to generate noise cancellation sounds, allowing for integrated voice recognition and noise cancellation functionality with fewer microphones placed further from occupants' ears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple noise-cancelling microphones are placed close to occupants' ears, then noise cancellation effectiveness is improved, but aesthetic appearance and cost efficiency deteriorate
Solution Approach 1:
The patent creates virtual microphone locations through signal processing that replicate the acoustic measurements that would be obtained from physical microphones placed near occupants' ears. The virtual microphone at location B provides the same noise cancellation information as a physical microphone would, eliminating the need for multiple expensive close-proximity microphones while maintaining effectiveness.
Solution Approach 2:
The patent introduces an intermediary signal processing system that transfers acoustic information from the actual microphone location A to a virtual location B near the occupant's ear. This intermediary process uses transfer functions and signal manipulation to bridge the gap between the physical microphone position and the desired virtual listening position, resolving the contradiction between microphone placement and aesthetic/cost concerns.
2Device complexity
If microphones are placed further from occupants' ears, then aesthetics and cost are improved, but noise cancellation precision at specific locations deteriorates
Solution Approach 1:
The patent replaces the mechanical solution of placing physical microphones near occupants' ears with a signal processing solution. Instead of mechanically positioning microphones in aesthetically poor locations, the system uses digital signal processing to create virtual microphone positions, substituting physical constraints with computational methods to maintain measurement precision.
Solution Approach 2:
The patent changes the parameters of the acoustic measurement system by transforming the spatial location parameter from physical to virtual. By modifying how location is defined (from physical microphone position to virtual acoustic position), the system achieves both distant physical microphone placement and precise noise measurement at the virtual location near the occupant's ear.
3Device complexity
If a single microphone is used for both voice recognition and noise cancellation, then cost and device complexity are reduced, but measurement precision for both functions may deteriorate
Solution Approach 1:
The patent makes a single physical microphone serve multiple functions by creating different virtual locations for different purposes. The same microphone signal is processed to create a virtual location A for voice recognition and a virtual location B for noise cancellation, allowing one physical device to perform multiple functions with high precision through signal processing differentiation.
Solution Approach 2:
The patent segments the single microphone signal into different virtual spatial locations that can be independently optimized for different functions. By dividing the acoustic information from one microphone into multiple virtual perspectives (location A for voice, location B for noise), the system maintains measurement precision for both functions while using fewer physical microphones.
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 enhances noise cancellation performance while reducing the number of microphones required, improving aesthetics and potentially lowering costs by allowing microphones to be positioned more than 34/F from the closest ear, effectively integrating noise cancellation with voice recognition.
Implementation Method 1
Active noise control ("ANC") systems may be implemented in a motor vehicle, e.g., an automobile, to reduce the amount of noise and undesired sounds that occupants are subjected to. Such systems typically include a microphone to receive noise and at least one loudspeaker to produce an inverted signal corresponding to the noise to be canceled.
Data Source
AI summary
Methods and apparatus are provided for controlling noise in a cabin of a vehicle. In various embodiments, a method for controlling noise in a cabin of a vehicle includes measuring a first sound via a microphone in the cabin; obtaining a second sound from a loudspeaker of the cabin; estimating, via a processor, a third sound at a virtual location that is remote from both the microphone and the loudspeaker, using the first sound, the second sound, and one or more transfer functions; and applying active noise cancellation for the cabin based on the third sound at the virtual location.