Active Noise Control Using High-Density Microphone Arrays
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Solution Overview
Problem
In closed structures like airplanes and trains, existing noise reduction methods either increase weight and fuel consumption with heavy sound insulation materials or require multiple microphones and speakers, increasing costs and complexity, while failing to effectively mitigate noise from multiple sources effectively.
Innovation Solution
A noise reduction device with a configuration of multiple microphones arranged in high density around seats to detect noise from various directions, combined with a control sound generator that emits phase-reversed sound waves to counteract noise, enhancing noise reduction efficiency and comfort by focusing on the strongest noise sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive attenuation means (sound insulation materials) are used to reduce noise, then noise reduction effect is achieved, but weight increases and fuel consumption increases
Solution Approach 1:
The patent replaces passive mechanical sound insulation materials with an active noise control system using microphones, controllers, and speakers to generate anti-phase sound waves. This substitutes heavy physical materials with electronic control systems, achieving noise reduction without increasing weight.
Solution Approach 2:
The system changes the phase parameter of sound waves by 180 degrees to create destructive interference with noise. By altering the phase parameter rather than using physical barriers, the system achieves noise attenuation without requiring heavy materials.
2Object-affected harmful factors
If multiple microphones and speakers are installed in each seat to effectively reduce noise, then noise reduction efficiency improves, but equipment cost and system complexity increase
Solution Approach 1:
The patent divides the airplane cabin into multiple zones and assigns different priority levels to noise sources in each zone. By segmenting the noise control problem spatially and hierarchically, the system achieves comprehensive noise reduction with fewer microphones and speakers than a uniform approach would require.
Solution Approach 2:
The system applies different noise control strategies to different locations based on their specific noise characteristics and priority levels. High-priority areas receive more focused control resources, while lower-priority areas use fewer resources, optimizing the overall system complexity versus effectiveness trade-off.
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 solution effectively reduces noise levels at seats by precisely detecting and counteracting noise from multiple sources, improving passenger comfort and reducing operational costs by minimizing the number of required microphones and speakers.
Implementation Method 1
a noise detector (microphone) for detecting noise emitted from noise sources
Implementation Method 2
a controller which amplifies the electric signal input from the microphone and reverses the phase
Implementation Method 3
a speaker which converts the electric signal input from the controller to sound and transmits the sound
Implementation Method 4
a method of reducing noise by using an active attenuation means, a conventional method of generating sound wave having a phase opposite to the phase of noise
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
It includes a microphone for detecting noise emitted from a noise source, a noise controller for generating control sound signal to reduce noise detected by the microphone based on information from the microphone, and a speaker for outputting control sound based on control sound signal from the noise controller, wherein a plurality of microphones and speakers are arranged for each seat, and a plurality of microphones are arranged in higher density for each seat in a specific direction.