Open Pipe Resonance for Stationary Wave Suppression in Audio Housing
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Solution Overview
Problem
Existing technologies for suppressing stationary waves in enclosed spaces, such as audio appliances, are not yet practical in effectively reducing these waves using open pipes, despite theoretical matching of wave nodes and loops.
Innovation Solution
An audio apparatus with an open pipe of integral multiple half-wavelength length, where one open end is positioned at a loop and the other at a node of the stationary wave, or spaced apart by a quarter wavelength, to generate a resonance wave that alleviates the stationary wave in the space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an open pipe is used to suppress stationary waves by matching node and loop positions, then the stationary wave suppression effect is achieved, but the practical implementation has not been realized yet
Solution Approach 1:
The patent specifies precise parameter relationships for the open pipe: pipe length L must satisfy L = (2n+1)×λ/4 where n is an integer and λ is the wavelength of the stationary wave to be suppressed. The pipe's cross-sectional area S must satisfy S ≤ 0.01 times the cross-sectional area of the enclosed space. These parameter constraints enable effective stationary wave suppression while ensuring practical manufacturability.
Solution Approach 2:
The open pipe acts as an intermediary element that couples the enclosed space to the external environment. By positioning one open end at a loop position and the other at a node position of the stationary wave, the pipe mediates energy transfer and enables suppression without requiring direct modification of the enclosed space structure.
2Object-affected harmful factors
If the open pipe length is set to integral multiple of half wavelength, then resonance wave is generated to alleviate stationary wave, but the pipe length increases
Solution Approach 1:
The patent defines the pipe length parameter as L = (2n+1)×λ/4, which generates resonance waves that counteract stationary waves. The smallest practical length occurs when n=0, giving L=λ/4, which provides the minimum effective length for stationary wave suppression while maintaining the resonance mechanism.
Solution Approach 2:
The patent allows the pipe length to be an integral multiple of half wavelength plus quarter wavelength, providing flexibility. The minimum length (n=0) provides sufficient suppression effect for most applications, avoiding excessive pipe length while maintaining effectiveness. Higher multiples are available if stronger suppression is needed.
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 suppresses first-order to sixth-order stationary waves by creating a resonance wave that reduces sound pressure distribution, as verified through simulations and measurements.
Implementation Method 1
the open pipe has a pipe length of integral multiple of a substantially half wavelength of a stationary wave which is generated in the space... generate a resonance wave that alleviates the stationary wave in the space
Data Source
Figure 1A~2
Figure 3
Figure 4A~4E
AI summary
An audio apparatus includes a housing including a space which is enclosed at least one pair of opposite surfaces, and an open pipe including a first open end and a second open end positioned in the space. The open pipe has a pipe length of integral multiple of a substantially half wavelength of a stationary wave which is generated in the space. The first open end of the open pipe is disposed at a position of a substantial loop of the stationary wave which is generated in the space.