Acoustic Impedance Matching Device With Gradient Absorber
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Solution Overview
Problem
Existing loudspeaker designs with acoustic impedance matching devices often suffer from undesirable distortions and frequency response modifications due to rear wave reflections, which are not adequately addressed by previous solutions that rely on high particle velocity and absorbent density, leading to non-linear phenomena and residual sound wave reflections.
Innovation Solution
An acoustic impedance matching device with a horn geometry where the section increases and absorbent material density increases away from the loudspeaker, reducing particle velocity and ensuring gradual absorption, thereby minimizing non-linear effects and reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high absorber density is used to increase sound absorption, then sound absorption is improved, but non-linear phenomena and reflections increase
Solution Approach 1:
The patent applies local quality by varying the density of the absorbing material along the length of the horn. The material has lower density near the loudspeaker and progressively higher density toward the far end, creating localized zones with different absorption characteristics. This gradient structure allows each section to optimize between absorption efficiency and non-linear effect minimization, resolving the contradiction between high sound absorption and reduced reflections.
2Loss of energy
If high particle velocity is used to increase sound absorption, then sound absorption is improved, but non-linear phenomena increase
Solution Approach 1:
The patent changes the physical parameter of particle velocity by designing a horn with increasing cross-sectional area from the loudspeaker end to the far end. This geometric progression causes particle velocity to decrease along the horn length, while simultaneously varying the absorbing material density to maintain effective absorption. This parameter transformation resolves the contradiction by achieving sound absorption through density variation rather than relying on high particle velocity.
3Loss of energy
If decreasing cross-section horn is used to increase particle velocity, then sound absorption is improved, but reflections towards loudspeaker increase
Solution Approach 1:
The patent inverts the conventional horn geometry by using an increasing cross-section design rather than a decreasing one. This inversion causes particle velocity to decrease along the horn length, which reduces non-linear effects and reflections. The compensation for reduced velocity is achieved through progressive increase in absorbing material density, thereby resolving the contradiction between absorption efficiency and reflection reduction.
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 configuration effectively reduces rear wave reflections and maintains acoustic performance across various sound levels by controlling absorption through progressive density variation, ensuring high absorption with reduced non-linearities and distortion.
Implementation Method 1
the sound absorption achieved within a fibrous material, textile, or open-cell foam is a transformation of acoustic energy into mechanical energy due to the interactions between moving air molecules and the material's structure
Implementation Method 2
The movement of air behind the diaphragm and inside the horn causes friction with the fibrous material, thus absorbing acoustic energy at the rear of the loudspeaker
Data Source
Figure 1~5
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Figure 10~12
AI summary
The invention relates to an acoustic impedance matching device (10) arranged so as to be mounted behind a loudspeaker (1). Said device comprises a chamber (11) at least partially filled with an absorbent material (14). Said device is characterized in that the cross-section of the chamber (11) increases with the distance from the loudspeaker (1), and the density of the absorbent material (14) increases with the distance from the loudspeaker (1).