Active Noise Reduction Control System with Variable Acoustic Ratios
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Solution Overview
Problem
Existing active noise cancellation systems for mobile phones and other loudspeaker systems struggle with variable acoustic conditions, leading to inadequate noise suppression due to unstable coupling between the speaker and the user's ear, which increases manufacturing and operational costs.
Innovation Solution
Implementing a control system that couples feedforward and feedback controls to different acoustic conditions, with the feedback control tuned for a tight seal and the feedforward control for a leaky seal, allowing each to compensate for changes in acoustic conditions, thereby maintaining effective noise suppression across a wide range of acoustic scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive control systems with adaptive filters are used to counteract variable acoustic conditions, then noise suppression performance is improved, but device complexity and manufacturing costs increase significantly
Solution Approach 1:
The patent applies dynamics by making the acoustic ratio variable rather than fixed. The system dynamically adjusts the acoustic ratio parameter to match different sealing conditions (tight seal vs. leaky seal) between the loudspeaker and user's ear, allowing the control system to adapt to variable acoustic conditions without requiring complex adaptive filters. This resolves the contradiction by achieving adaptability through a simpler parameter adjustment mechanism.
Solution Approach 2:
The patent changes the acoustic ratio parameter to resolve the technical contradiction. By varying the acoustic ratio between a first value (for tight seal conditions) and a second value (for leaky seal conditions), the system achieves good noise suppression performance across different acoustic conditions without implementing complex adaptive control systems, thereby reducing device complexity and manufacturing costs.
2Reliability
If feedforward control is tuned for high bandwidth while reverse control is tuned for narrower bandwidth, then overall noise suppression is improved, but device complexity increases
Solution Approach 1:
The patent applies dynamics by making the acoustic ratio variable rather than fixed. The system dynamically adjusts the acoustic ratio parameter to match different sealing conditions (tight seal vs. leaky seal) between the loudspeaker and user's ear, allowing the control system to adapt to variable acoustic conditions without requiring complex adaptive filters. This resolves the contradiction by achieving adaptability through a simpler parameter adjustment mechanism.
Solution Approach 2:
The patent changes the acoustic ratio parameter to resolve the technical contradiction. By varying the acoustic ratio between a first value (for tight seal conditions) and a second value (for leaky seal conditions), the system achieves good noise suppression performance across different acoustic conditions without implementing complex adaptive control systems, thereby reducing device complexity and manufacturing costs.
3Ease of operation
If the loudspeaker coupling to the user's ear is variable due to user behavior, then ease of operation is improved, but noise suppression performance deteriorates
Solution Approach 1:
The patent applies dynamics by making the acoustic ratio variable rather than fixed. The system dynamically adjusts the acoustic ratio parameter to match different sealing conditions (tight seal vs. leaky seal) between the loudspeaker and user's ear, allowing the control system to adapt to variable acoustic conditions without requiring complex adaptive filters. This resolves the contradiction by achieving adaptability through a simpler parameter adjustment mechanism.
Solution Approach 2:
The patent changes the acoustic ratio parameter to resolve the technical contradiction. By varying the acoustic ratio between a first value (for tight seal conditions) and a second value (for leaky seal conditions), the system achieves good noise suppression performance across different acoustic conditions without implementing complex adaptive control systems, thereby reducing device complexity and manufacturing costs.
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 ensures robust noise suppression across varying acoustic conditions with reduced power and manufacturing costs, making it suitable for the mobile radio sector where user behavior affects acoustic conditions.
Implementation Method 1
The inverted signal thus emitted by the speaker interferes with the noise arriving at the ear via path 1 to effect cancellation of unwanted noise
Data Source
AI summary
The invention relates to a closed loop control system for active noise reduction, comprising a speaker and an adding device connected to the speaker. A feedforward control and a feedback control each comprise a microphone for recording noise interference or for recording a sound output by the speaker. Control networks for forming a corresponding control parameter are coupled to the corresponding microphones and are connected to the adding device at the output side thereof. According to the invention, the feedback control for noise reduction is adapted on the basis of a first acoustic ratio and the feedforward control for noise reduction is adapted on the basis of a second acoustic ratio. The control network of the feedback control is designed to at least partially compensate for the control parameter of the feedforward control when current acoustic ratios change in the direction of the first acoustic ratio.