Acoustic Cavity Area Variation Standing Wave Control
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Solution Overview
Problem
Existing acoustic structures face challenges in controlling standing waves within their cavities, leading to disturbances in frequency characteristics across a wide frequency range, and existing solutions either fail to effectively suppress standing waves or increase production costs due to the use of sound absorbers.
Innovation Solution
The acoustic structure is designed with specific modifications, such as varying the cross-sectional area at the node or antinode positions of standing waves within the cavity, and incorporating open tubes with specific lengths and sound absorbers to control the resonance frequency and mitigate standing wave disturbances without increasing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sound absorbers are provided in the cavity to suppress standing waves, then the standing wave suppression effect is improved, but the production cost increases
Solution Approach 1:
The cavity structure itself serves as the standing wave suppression mechanism through its geometric design (tapered shape, irregular cross-section), eliminating the need for separate sound absorber components. The structure performs both its primary function of housing acoustic elements and the secondary function of suppressing standing waves.
Solution Approach 2:
The cavity's geometric parameters (cross-sectional area, length, shape) are specifically designed to create acoustic impedance variations that suppress standing waves. By changing the physical parameters of the cavity structure itself rather than adding separate components, the invention achieves suppression without increasing production cost.
2Ease of manufacture
If the cavity is designed as a uniform tube to simplify manufacturing, then the ease of manufacture is improved, but the ability to control specific frequency standing waves deteriorates
Solution Approach 1:
The cavity is designed with non-uniform cross-sectional area along its length, creating local variations in acoustic impedance at specific positions. These localized geometric changes target specific frequency ranges for standing wave suppression while maintaining overall structural simplicity.
Solution Approach 2:
The cavity is divided into multiple sections with different cross-sectional areas, allowing each section to address different frequency ranges. This segmentation enables targeted control of standing waves at specific frequencies without requiring complete redesign of the entire cavity structure.
3Device complexity
If conventional acoustic structures are used without area variations, then the device complexity is reduced, but the frequency characteristics are disturbed by standing waves
Solution Approach 1:
The cavity employs curved or tapered transitions in cross-sectional area rather than abrupt changes, creating smooth acoustic impedance variations. This curved design suppresses standing waves by avoiding sharp reflections while maintaining relatively simple manufacturing compared to complex multi-component 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
This approach effectively shifts the resonance frequency, reduces peak values, and minimizes disturbances in frequency characteristics across all frequency ranges without the need for additional sound absorbers, thereby enhancing the acoustic structure's performance and maintaining cost-effectiveness.
Implementation Method 1
there is generated a standing wave by superposition of the sound wave and reflected waves on a wall surface that defines the cavity
Implementation Method 2
a first portion of the cavity substantially corresponding to a position of a node or an antinode of a standing wave generated in the cavity has an area different from an area of a second portion of the cavity
Data Source
Figure 1A~2B
Figure 3~4
Figure 5~6
AI summary
An acoustic structure (20A, 20A'; 20B; 20C; 20D; 20E1, 20E2, 20E3; 20F1, 20F2, 20F3; 20G) defining a cavity in which a sound wave propagates, wherein a first portion (2LH) of the cavity substantially corresponding to a position of a node or an antinode of a standing wave generated in the cavity has an area different from an area of a second portion of the cavity except the first portion, the area being on a plane orthogonal to a direction of propagation of the sound wave.