Loudspeaker-Integrated Error Sensing for Fast Active Noise Cancellation
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Solution Overview
Problem
Active noise control systems in harsh environments, such as high-temperature exhaust systems, face performance issues due to temperature fluctuations affecting the speed of sound and resulting in increased response times that exceed typical noise control processing delays.
Innovation Solution
The system reduces the secondary path length between the loudspeaker and error microphone, and employs adaptive noise filters with eigenvalue decomposition and stability conditions to compensate for temperature-induced uncertainties, allowing for faster noise cancellation without modifying the signal processing structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the error microphone is positioned farther from the loudspeaker to accurately measure residual noise, then measurement precision is improved, but the secondary path delay increases causing slower response time
Solution Approach 1:
The error microphone is nested within the loudspeaker structure by positioning it in the front face acoustic outlet area. This allows the microphone to be physically integrated into the loudspeaker assembly, minimizing the distance between the loudspeaker diaphragm and the error sensor while still capturing the anti-noise sound field characteristics for accurate measurement.
Solution Approach 2:
The patent introduces a acoustic error sensor as an intermediary element that can be positioned close to the loudspeaker front face. This sensor serves as a mediator that captures the anti-noise sound field without requiring large separation distances, thereby reducing secondary path delay while maintaining measurement capability through its strategic positioning in the acoustic outlet area.
2Loss of time
If the error microphone is positioned close to the loudspeaker to reduce secondary path delay, then response time is improved, but measurement precision deteriorates due to proximity effects
Solution Approach 1:
The error microphone is positioned in a specific local area of the loudspeaker front face acoustic outlet. This localized positioning allows the sensor to capture the anti-noise sound field characteristics at the critical acoustic outlet region while maintaining adequate separation from the loudspeaker diaphragm to avoid proximity effects, thus achieving both fast response and accurate measurement.
3Object-generated harmful factors
If traditional ANC systems are used in high-temperature environments, then noise cancellation is provided, but system reliability deteriorates due to temperature-induced speed of sound variations
Solution Approach 1:
The system employs an error microphone positioned in the front face acoustic outlet to provide real-time feedback on the anti-noise sound field. This feedback mechanism allows the active noise controller to continuously monitor and adjust the anti-noise signal based on actual conditions, compensating for temperature-induced speed of sound variations and maintaining reliable noise cancellation performance in high-temperature environments.
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 reduces noise control response time, enhancing the system's performance in high-temperature environments by minimizing latency and maintaining robustness against temperature fluctuations.
Implementation Method 1
a loudspeaker operatively coupled to the active noise controller and configured to convert the anti-noise signal into anti-noise sound
Implementation Method 2
An acoustic error sensor operatively coupled to the active noise controller is configured to pick up sound and to convert the picked-up sound into the error signal
Data Source
AI summary
An active noise cancellation system and method, in which an active noise controller generates an anti-noise signal based on an error signal, and a loudspeaker operatively coupled to the active noise controller converts the anti-noise signal into anti-noise sound. An acoustic error sensor operatively coupled to the active noise controller picks up sound and converts the picked-up sound into the error signal. The acoustic error sensor is disposed at a front face of the loudspeaker.