Active Noise Reduction Controller Propagation Distance Compensation
Solution Overview
Problem
In active noise reduction systems, an increase in the canceling sound propagation distance can lead to a deterioration of the noise reduction effect at the user's ear position or even amplification of noise, due to the need for a larger canceling sound output.
Innovation Solution
The system incorporates a controller that calculates the canceling sound propagation distance and adjusts the canceling sound output accordingly, suppressing changes in the canceling sound to maintain effective noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the canceling sound propagation distance increases, then the noise reduction effect at the error microphone position is maintained, but the noise reduction effect at the user's ear position deteriorates or noise is amplified
Solution Approach 1:
The patent changes the parameter of canceling sound output level based on the canceling sound propagation distance. When the propagation distance increases, the controller adjusts the output level of the canceling sound to prevent excessive amplification at the user's ear position while maintaining noise reduction effectiveness at the error microphone position.
2Reliability
If a larger canceling sound output is used to compensate for increased propagation distance, then the noise reduction at the error microphone position is sufficient, but the noise reduction effect at the user's ear position deteriorates
Solution Approach 1:
The system uses feedback from the error microphone to monitor the noise and canceling sound levels. The controller continuously adjusts the canceling sound output based on the error signal and propagation distance information, ensuring that the noise reduction performance remains consistent across different positions including both the error microphone location and the user's ear position.
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 prevents the noise reduction effect from being reduced at the user's ear position and avoids noise amplification, ensuring consistent noise reduction performance even as the canceling sound propagation distance increases.
Implementation Method 1
an active noise reduction system, which reduces the noise by causing a canceling sound that is in an opposite phase to the noise to interfere with the noise
Data Source
AI summary
An active noise reduction system includes a canceling sound output device configured to output a canceling sound for canceling a noise, an error microphone configured to generate an error signal based on the noise and the canceling sound, and a controller configured to control the canceling sound output device based on the error signal, wherein the controller is configured to calculate a canceling sound propagation distance that is a distance from the canceling sound output device to the error microphone, and suppress a change in the canceling sound based on the canceling sound propagation distance.