Tunable Acoustic Structure for Low-Frequency Sound Attenuation
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Solution Overview
Problem
Existing sound modifying structures fail to effectively mitigate low-frequency sound in enclosed spaces, as they lack efficient frequency-tunable solutions for sound absorption and radiation.
Innovation Solution
The implementation of a frequency-tunable acoustic structure comprising a cone-shaped acoustic fireplace connected to an acoustic waveguide duct system, including a tunable anti-noise source and a Helmholtz resonator, which absorbs sound and radiates it outside through an adjustable acoustic chimney, utilizing exponential tapered horns for impedance matching and sound propagation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional sound modifying structures are used, then high-frequency sound can be mitigated, but low-frequency sound cannot be effectively absorbed or radiated
Solution Approach 1:
The acoustic structure employs adjustable components including movable plugs within the waveguide duct and adjustable acoustic chimneys that can be positioned at different heights. These dynamic elements allow the system to adapt its acoustic impedance and resonance characteristics to effectively target low-frequency sound waves, which conventional static structures cannot address
Solution Approach 2:
The system changes acoustic parameters by adjusting the position of plugs within the waveguide duct and modifying the extension height of acoustic chimneys. These parameter adjustments alter the resonant frequencies and absorption characteristics of the structure, enabling effective low-frequency sound mitigation that was previously unachievable with fixed conventional designs
2Object-affected harmful factors
If sound is absorbed within the acoustic fireplace, then sound intensity levels are reduced, but the acoustic energy must be effectively radiated outside through the chimney
Solution Approach 1:
The waveguide duct system acts as an intermediary between the acoustic fireplace (absorption chamber) and the acoustic chimneys (radiation elements). This intermediate structure efficiently couples the absorbed acoustic energy to the radiation mechanism, enabling effective sound intensity reduction while maintaining a manageable and integrated device architecture
Solution Approach 2:
The acoustic structure employs a nested configuration where acoustic chimneys are positioned within or adjacent to the waveguide duct system, which itself is connected to the acoustic fireplace. This nested arrangement allows compact integration of the absorption and radiation functions, reducing overall device complexity while maintaining effective acoustic energy transfer from absorption to radiation
3Ease of operation
If exponential tapered horns are used for impedance matching, then sound propagation is improved, but the structure requires precise geometric control
Solution Approach 1:
Rather than relying solely on precise fixed geometric control of exponential tapered horns, the system uses adjustable plugs and movable components within the waveguide duct. These dynamic elements provide real-time impedance matching and sound propagation optimization, reducing the need for extremely precise manufacturing tolerances on the horn geometries themselves
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
This solution effectively attenuates low-frequency sound by absorbing it within the acoustic fireplace and radiating it outside through the chimney, reducing sound intensity levels and minimizing resonance frequencies, thereby improving sound isolation and reducing noise pollution in enclosed environments.
Implementation Method 1
absorbing it within the acoustic fireplace
Implementation Method 2
a Helmholtz resonator
Implementation Method 3
utilizing exponential tapered horns for impedance matching and sound propagation control
Implementation Method 4
an acoustic waveguide duct system
Data Source
AI summary
An acoustic structure and a method for dampening sound. The acoustic structure includes an acoustic absorber having one or more acoustic elements. The acoustic absorber is disposed inside a volume. The acoustic structure further includes an acoustic radiator having one or more acoustic elements. The acoustic radiator is disposed outside the volume. A cross-sectional area of the one or more acoustic elements decreases with a distance from a mouth of the one or more acoustic elements to a throat of the one or more acoustic elements. The acoustic structure also includes one or more acoustic waveguide ducts configured to acoustically couple the acoustic absorber and the acoustic radiator.