Ultra-thin Schroeder Diffuser with Varying Neck Widths
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Solution Overview
Problem
Conventional Schroeder acoustic structures are thick and bulky, making them unsuitable for integration with other acoustic devices due to their uniform unit cell dimensions and resulting thickness of λ/2, which limits their practical application.
Innovation Solution
An ultra-thin Schroeder diffuser with a thickness of λ/20 is designed, featuring 7×p rows and 7×q columns of unit cells, where the side length of the square unit cell is 0.48λ, and the unit cell includes a square neck with a depth of 0.04λ and varying neck widths, optimized for phase distribution around a center frequency or multiple frequencies, achieving diffuse reflection within a specific bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional Schroeder diffuser structure is used with uniform unit cells, then the acoustic diffusion function is achieved, but the thickness becomes too large (λ/2) for practical integration
Solution Approach 1:
The patent applies local quality by making each unit cell non-uniform: the neck width varies across different positions according to a specific sequence, while the depth remains uniform. This local variation in neck width creates the necessary phase distribution for acoustic diffusion without requiring large thickness, thus resolving the contradiction between thin profile and acoustic performance
Solution Approach 2:
The patent changes the geometric parameters of the unit cells, specifically varying the neck width parameter across the array according to a Schroeder sequence while maintaining uniform depth. This parameter variation enables the thin structure (λ/20) to achieve the acoustic diffusion effect previously requiring λ/2 thickness
2Adaptability or versatility
If uniform unit cell dimensions are used, then manufacturing is simplified, but the acoustic diffusion bandwidth is limited
Solution Approach 1:
The patent implements local quality by assigning different neck widths to different unit cells based on their position in the array, following a Schroeder sequence. This local differentiation expands the effective bandwidth for acoustic diffusion while maintaining a relatively simple overall structure that is still manufacturable
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 ultra-thin diffuser achieves broadband sound wave diffuse reflection with comparable performance to conventional Schroeder diffusers while significantly reducing material thickness, facilitating easier integration and use in acoustic devices.
Implementation Method 1
a depth of the square unit cell is 0.04λ, the unit cell is provided with a square neck, a side length of the square neck is less than the side length of the unit cell, a depth of the neck is 0.01λ
Implementation Method 2
the neck widths w of different unit cells are different, and a distribution of the widths satisfies a certain sequence, so that expected phase distribution is achieved in the center frequency or multiple frequencies around the center frequency
Data Source
AI summary
An ultra-thin Schroeder diffuser comprises a backing-plate, wherein the backing-plate is provided with 7×p rows and 7×q columns of unit cells, p and q are integers greater than or equal to 1, a side length of the unit cell is 0.48λ, a depth of the square unit cell is 0.04λ, the unit cell is provided with a square neck, a side length of the square neck is less than the side length of the unit cell, a depth of the neck is 0.01λ, λ is a wavelength of the diffuser corresponding to the design at a center frequency center f0, the neck widths w of different unit cells are different, and a distribution of the widths satisfies a certain sequence.