Resonance Soundproof Structure Positioning for Phase-Offset Absorption
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Solution Overview
Problem
Existing soundproof structures face challenges in compactly absorbing low-frequency sound and efficiently handling peak noise, particularly in spatially restricted environments, and require multiple resonators for high absorption, which is not suitable for miniaturization.
Innovation Solution
A soundproof structure with a tubular tube body and a resonance type soundproof structure where the phase difference between reflected waves satisfies a specific condition, using a single resonance structure to enhance absorption, and strategically positioning it near the opening to offset reflections, allowing for high absorption with a smaller number of structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a silencer box with larger cross-sectional area than the ventilation duct is used to absorb low frequency sound, then low frequency sound absorption is improved, but the device configuration becomes large and cannot be compact
Solution Approach 1:
The resonance type soundproof structure is nested within the ventilation duct without requiring an outer silencer box. The resonance body is positioned inside the duct cross-section, utilizing the duct's own space rather than adding external volume, thus achieving compact low-frequency sound absorption.
Solution Approach 2:
Instead of expanding the duct cross-sectional area in two dimensions to create a silencer box, the invention uses a resonance body that operates in the acoustic dimension by creating controlled reflections and interference patterns, achieving sound absorption without dimensional expansion.
2Object-affected harmful factors
If multiple resonance type soundproof structures are disposed in parallel to increase sound absorbance, then sound absorbance is improved, but the device complexity and number of structures increase
Solution Approach 1:
The invention optimizes the parameters of a single resonance type soundproof structure, specifically positioning it where the phase difference between reflected waves satisfies a specific condition. This parameter optimization allows one structure to achieve the absorbance that would traditionally require multiple structures.
Solution Approach 2:
The resonance type soundproof structure is strategically positioned in advance at a location where the phase relationship between reflected waves can be controlled. By pre-positioning the structure to exploit wave interference effects, high absorbance is achieved with minimal structures.
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 absorbs sound with a smaller size and fewer structures, improving soundproofing efficiency by aligning the phase of reflected waves to cancel each other out, achieving high absorption rates.
Implementation Method 1
a resonance type soundproof structure (a resonance body such as a Helmholtz resonator, an air column resonance cylinder, and a film vibration type resonance structure) into a duct
Implementation Method 2
a part of sound propagating in the ventilation duct, particularly low frequency sound, is transmitted from the sound absorbing duct into the silencer box and then returned to the ventilation duct due to the phenomenon of sound reflection at an opening end
Implementation Method 3
an interval between the resonant openings of the two resonators is an interval in which the resonant opening of the resonator on the upstream faces toward a position at which sound pressure in the frequency band to be silenced increases due to interference between sound propagated from a sound source and sound reflected from the resonator on the downstream
Data Source
AI summary
In a soundproof structure body including a tubular tube body having an opening portion, and a resonance type soundproof structure, in which a phase difference θ, at an upstream of the resonance type soundproof structure, between a reflected wave in the resonance type soundproof structure and a reflected wave of a transmitted wave transmitted through the resonance type soundproof structure and reflected by the opening portion satisfies Inequation |θ−π|≤π/3 with respect to a resonance frequency of the resonance type soundproof structure. This soundproof structure body can effectively offset a reflected wave from a resonance type soundproof structure body by opening end reflection by appropriately specifying positions of the resonance type soundproof structure and the opening end portion of a duct, a tube line, or the like to improve an absorbance of a single resonance type soundproof structure.