Soundproof Structure Combining Membrane Vibration and Helmholtz Resonance
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Solution Overview
Problem
Existing soundproof structures struggle to effectively reduce high-frequency noise from electronic devices and motors, as conventional methods like porous sound absorbing bodies and Helmholtz resonance struggle to absorb specific frequency sounds, and combining different sound reduction means often requires significant space and weight, which is not feasible in compact electronic systems.
Innovation Solution
A soundproof structure incorporating a plate-like member with through-holes, a membrane-like member, and a support that utilizes both membrane vibration and Helmholtz resonance, where the fundamental frequency of Helmholtz resonance is twice or more than the fundamental frequency of membrane vibration, allowing for efficient absorption of high-frequency sounds across multiple frequency bands in a compact and lightweight design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If porous sound absorbing body is used, then sound reduction effect is obtained in wide frequency range, but specific frequency sound is not sufficiently reduced
Solution Approach 1:
The patent combines two different sound reduction mechanisms: a porous sound absorbing body for broadband noise reduction and a Helmholtz resonator for specific frequency noise reduction. The porous material absorbs sound across a wide frequency range while the Helmholtz resonator targets specific problematic frequencies, achieving both wide frequency coverage and effective specific frequency reduction simultaneously.
Solution Approach 2:
The soundproof structure uses composite construction by integrating porous sound absorbing material with a Helmholtz resonator cavity structure. This composite approach allows the system to leverage the strengths of both mechanisms: the porous material's broadband absorption and the resonator's frequency-selective absorption, resolving the contradiction between wide frequency coverage and specific frequency effectiveness.
2Reliability
If large amount of porous sound absorbing body is used, then louder sound is reduced, but space for disposing sound absorbing body is insufficient
Solution Approach 1:
The patent changes the sound reduction mechanism from relying solely on porous absorption to incorporating Helmholtz resonance. By adjusting the resonator parameters (cavity volume, neck dimensions) to match the target frequency, the system achieves effective sound reduction with a compact structure, eliminating the need for large volumes of porous material while maintaining or improving sound reduction effectiveness.
3Reliability
If sound reduction means using Helmholtz resonance is used, then specific frequency sound is reduced significantly, but sound in multiple frequency bands cannot be reduced simultaneously
Solution Approach 1:
The patent merges Helmholtz resonance with porous sound absorption to create a hybrid system. The Helmholtz resonator provides strong attenuation at its resonant frequency, while the porous material simultaneously absorbs sound across a broader frequency spectrum. This combination allows the system to reduce specific frequency sounds significantly while also handling multiple frequency bands, achieving both targeted and broadband noise reduction.
4Adaptability or versatility
If different sound reduction means are combined, then sound in multiple frequency bands is reduced, but device complexity and weight increase
Solution Approach 1:
The patent designs the soundproof structure to serve multiple functions within a single integrated system. The porous sound absorbing body provides broadband noise reduction while the Helmholtz resonator component targets specific frequencies, allowing the entire structure to handle multiple frequency bands simultaneously. This multi-functional design achieves versatile sound reduction without proportionally increasing complexity, as both mechanisms work together in a unified structure.
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 proposed structure achieves significant sound absorption across a wide frequency range, including high-frequency sounds, while maintaining a small and lightweight form factor, effectively addressing the limitations of existing technologies by enhancing sound absorption coefficients in high-order vibration modes and Helmholtz resonance frequencies.
Implementation Method 1
a membrane-like member that is disposed to face one surface of the plate-like member; and a support that is formed of a rigid body and supports the plate-like member and the membrane-like member, in which the membrane-like member is supported by the support so as to perform membrane vibration
Implementation Method 2
the plate-like member having the through-hole, the support, the membrane-like member, and the first space form a second sound absorbing portion that absorbs a sound by Helmholtz resonance
Data Source
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AI summary
Provided is a soundproof structure that is small and light and can reduce a noise with a high specific frequency of a sound source at a plurality of frequencies at the same time. A soundproof structure includes a plate-like member in which at least one through-hole is formed, a membrane-like member that is disposed to face one surface of the plate-like member, and a support that is formed of a rigid body and supports the plate-like member and the membrane-like member, in which the membrane-like member is supported by the support so as to perform membrane vibration, in which a first space is provided between the plate-like member and the membrane-like member, in which a rear surface space is provided on a side opposite to the first space with the membrane-like member sandwiched therebetween, in which the membrane-like member, the support, and the rear surface space form a first sound absorbing portion that absorbs a sound by membrane vibration, in which the plate-like member having the through-hole, the support, the membrane-like member, and the first space form a second sound absorbing portion that absorbs a sound by Helmholtz resonance, and in which assuming that a fundamental frequency of the Helmholtz resonance in a case where the membrane-like member is regarded as the rigid body in the second sound absorbing portion is fh1 and a fundamental frequency of the membrane vibration of the second sound absorbing portion is denoted by fm1, fh1 ≥ 2 × fm1 is satisfied.