Sub-band Noise Reduction for Low-Frequency Suppression
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Solution Overview
Problem
Conventional noise reduction techniques, including passive and active noise reduction methods, are ineffective in reducing low-frequency noise, particularly when using a full-band noise reduction approach, which limits their noise suppression performance.
Innovation Solution
A sub-band noise reduction system that employs a sub-band noise sensor and multiple sub-band noise reduction modules to generate and process noise signals across distinct frequency bands, using band-pass filters and modulators to create correction signals that effectively cancel out noise across specific sub-bands, thereby improving noise reduction efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a full-band noise reduction technique is used, then the system structure is simple, but the noise reduction effect is poor especially for low-frequency noise
Solution Approach 1:
The patent divides the full-band noise reduction system into multiple sub-band noise reduction modules, each handling a specific frequency range. The noise signal is decomposed into multiple sub-band signals through frequency division, allowing each module to specialize in reducing noise within its designated sub-band, thereby improving overall noise reduction effectiveness while managing system complexity through modular design
2Reliability
If passive noise reduction techniques are used, then the system is simple to implement, but the noise reduction effect is poor under certain conditions
Solution Approach 1:
The patent replaces passive mechanical noise blocking methods with active electronic signal processing. Instead of relying on physical barriers to block noise, the system uses electronic sensors to detect noise signals and generates anti-phase correction signals through electronic circuits, enabling effective noise reduction particularly for low-frequency noise that passive methods cannot handle
3Reliability
If active noise reduction is used for low-frequency noise, then the noise reduction effect improves, but the system complexity increases
Solution Approach 1:
The patent implements low-frequency noise reduction by segmenting the frequency spectrum into multiple sub-bands, with dedicated noise reduction modules for different frequency ranges. This allows the system to focus computational resources and hardware complexity only on the sub-bands where noise reduction is needed, rather than processing the entire frequency spectrum uniformly
Solution Approach 2:
The patent applies different noise reduction strategies to different frequency sub-bands based on their specific characteristics. Each sub-band noise reduction module is optimized for its designated frequency range, allowing the system to achieve effective low-frequency noise reduction while using simpler processing for other frequency ranges where less complex methods suffice
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
The sub-band noise reduction system enhances noise suppression by targeting specific frequency bands, leading to improved noise reduction performance compared to full-band techniques, particularly in scenarios with low-frequency noise, and can be applied in various devices such as headphones and audio broadcast systems.
Implementation Method 1
The acoustic-electric transducer may be configured to detect the noise and convert the noise into an electrical signal
Implementation Method 2
The band dividing module may include a plurality of band-pass filters. Each of the band-pass filters may have a unique frequency response and be configured to generate one of the sub-band noise signals
Implementation Method 3
an active noise reduction (ANR) technique has been adopted to reduce noises in an active manner by generating a noise reduction signal (e.g., a signal having an inversed phase to the noise to be reduced)
Implementation Method 4
The output module may be configured to receive the sub-band noise correction signals and output a noise correction signal for reducing the noise based on the sub-band noise correction signals
Data Source
AI summary
A noise reduction system is provided. The noise reduction system may include a sub-band noise sensor, a plurality of sub-band noise reduction modules, and an output module. The sub-band noise sensor may be configured to detect a noise and generate a plurality of sub-band noise signals in response to the detected noise. Each of the plurality of sub-band noise signals may have a distinctive sub-band of the frequency band of the noise. Each of the sub-band noise reduction modules may be configured to receive one of the sub-band noise signals from the sub-band noise sensor and generate a sub-band noise correction signal for reducing the received sub-band noise signal. The output module may be configured to receive the sub-band noise correction signals and output a noise correction signal for reducing the noise based on the sub-band noise correction signals.