Dynamic Speaker Configuration for Noise Cancellation Zone Expansion
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Solution Overview
Problem
Conventional noise cancellation systems fail to effectively cancel noise across a wide spatial region due to a mismatch between the noise field and the driver field, leading to inefficient noise cancellation and audible artifacts when the occupant turns their head, and can cause amplifier clipping during certain noise events.
Innovation Solution
The system employs arrayed speakers to produce a substantially uniform sound pressure field that matches the noise field in magnitude but with inverted phase over a larger spatial region, and transitions to an in-phase configuration during noise-related events to prevent amplifier clipping, thereby increasing the noise cancellation zone and maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If speakers are driven in an arrayed configuration to produce a uniform sound pressure field, then the noise cancellation zone is expanded, but the system becomes susceptible to amplifier clipping during high-amplitude noise events
Solution Approach 1:
The system dynamically switches between arrayed and in-phase speaker configurations based on real-time noise level detection. During normal conditions, arrayed configuration expands the noise cancellation zone. When high-amplitude noise events are detected, the system transitions to in-phase configuration to prevent amplifier clipping, then returns to arrayed configuration when noise levels normalize.
Solution Approach 2:
The system changes the operational parameters of the speaker system by switching between two distinct configurations: arrayed configuration for normal noise levels and in-phase configuration for high-amplitude events. This parameter change allows the system to adapt to varying noise conditions and prevent clipping while maintaining effective noise cancellation.
2Reliability
If speakers are driven in an in-phase configuration to prevent amplifier clipping, then amplifier clipping is avoided, but the noise cancellation effectiveness decreases
Solution Approach 1:
The system employs periodic switching between arrayed and in-phase configurations based on the periodic nature of noise events. During normal operation, arrayed configuration provides effective noise cancellation. When noise events occur, the system periodically switches to in-phase configuration to prevent clipping, then returns to arrayed configuration after the event subsides, maintaining overall noise cancellation effectiveness.
Solution Approach 2:
The system uses feedback from noise level detection to automatically switch between configurations. The feedback mechanism monitors noise amplitude and triggers configuration changes only when necessary, ensuring that in-phase configuration is used sparingly only when amplifier clipping is at risk, thereby maintaining noise cancellation effectiveness during most operating conditions.
3Device complexity
If a single speaker configuration is used to simplify the system, then device complexity is reduced, but the system cannot adapt to different noise conditions
Solution Approach 1:
The speaker system performs multiple functions by implementing both arrayed and in-phase configurations within a single system. The arrayed configuration handles normal noise cancellation tasks, while the in-phase configuration provides protection against amplifier clipping during high-amplitude events. This multi-functionality is achieved through a unified system that automatically selects the appropriate configuration based on noise conditions.
Solution Approach 2:
The system introduces dynamic adaptability by allowing real-time switching between speaker configurations based on detected noise levels. This dynamic behavior enables the system to adapt to varying acoustic environments without requiring multiple separate systems, maintaining relatively simple device complexity while significantly improving adaptability to different noise conditions.
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 significantly expands the noise cancellation zone around the occupant, reducing noise-related discomfort and preventing amplifier clipping, while maintaining efficient noise cancellation by dynamically adjusting the speaker configuration in response to noise events.
Implementation Method 1
the speakers are arrayed to produce a substantially uniform (i.e., flat) driver field that closely matches the noise field in magnitude with the opposite phase within the cancellation zone
Implementation Method 2
Conventional noise cancellation systems generally use feedback from a microphone picking up noise to control a speaker such that the sound from the speaker cancels the noise at the microphone
Data Source
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AI summary
A noise cancellation method and system comprises a system controller that produces a command signal in response to a signal from at least one microphone detecting sound in an area. The system controller includes an arrayed speaker controller for producing a driver signal for each speaker in response to the command signal such that combined sound emitted by the speakers in response to the driver signals produces a substantially uniform sound pressure field adapted to attenuate a noise field corresponding to the sound detected by the at least one microphone. The system controller includes an in-phase speaker controller for producing a common in-phase driver signal for all speakers in response to the command signal and a signal director module for proportioning the command signal between the arrayed and in-phase speaker controllers in response to a magnitude of voltage associated with driving the speakers in accordance with the command signal.