Perforated Layer Wind Filter for Microphones
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Solution Overview
Problem
Wind noise significantly degrades speech signals in microphones used in hand portable radio communication units, especially in windy environments, and existing solutions requiring large amounts of open cell foam material are not suitable for compact devices.
Innovation Solution
A compact wind filter device with a substrate having an aperture, a first layer with a perforated region over the aperture, and a second layer with another perforated region, along with a spacer ring to create an enclosed space, which provides high dynamic resistance to wind noise while maintaining low resistance for speech sounds, effectively filtering out wind noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If open cell foam material is used to reduce wind noise, then wind noise reduction is improved, but device size and compactness deteriorate
Solution Approach 1:
The wind filter device is divided into multiple functional layers: a substrate layer with an aperture, a first layer with a perforated region, and a second layer with another perforated region. Each layer contributes to wind noise reduction through its specific structure, achieving effective filtering without requiring a single large foam material
Solution Approach 2:
The invention uses porous materials with specific perforation patterns rather than traditional open cell foam. The substrate, first layer, and second layer all contain apertures or perforations that allow speech frequencies to pass while creating sufficient resistance to high-frequency wind noise, achieving the same noise reduction effect with much smaller dimensions
2Object-affected harmful factors
If protective covering is added over the microphone, then wind noise reduction is improved, but microphone sensitivity deteriorates
Solution Approach 1:
Different regions of the wind filter device have different properties optimized for specific functions: the substrate provides structural support with an aperture, the first layer has a perforated region optimized for speech frequencies, and the second layer has another perforated region for additional filtering. This localized optimization allows wind noise reduction while preserving speech signal quality and microphone sensitivity
Solution Approach 2:
The wind filter device combines multiple materials with different properties: a substrate material providing structural integrity, a first layer material with specific perforation characteristics, and a second layer material with complementary filtering properties. This composite structure achieves both wind noise reduction and speech signal preservation that single-material solutions cannot achieve
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 wind filter device significantly reduces wind noise by approximately 12 dB, maintaining the microphone's sensitivity and compactness, and further improvements can reduce noise by an additional 6 dB with a woven mesh layer.
Implementation Method 1
provides high dynamic resistance to wind noise while maintaining low resistance for speech sounds
Implementation Method 2
The wind filter device significantly reduces wind noise by approximately 12 dB
Data Source
AI summary
A wind filter device (215) for use with a microphone (203), the wind filter device including a substrate (219) having an aperture (221) extending through the substrate, attached to a first face of the substrate a first layer (223) having a first perforated region (228) over the aperture and, attached to a second face of the substrate, a second layer (225) having a second perforated region (228) over the aperture. Also described is an arrangement of the wind filter device and a microphone, and a hand portable radio communication unit including the arrangement.