Sound Scattering Properties of Surfaces with Diffusers

Marina Lavrova,Nikolay Kanev,A.I Komkin,A.I Bykov

doi:10.1051/matecconf/202032000024

Marina Lavrova, Nikolay Kanev + Show 2 more

Open Access

https://doi.org/10.1051/matecconf/202032000024

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Abstract

This article compares the values of the normal scattering coefficient measured in a model experiment for two types of diffusers placed on a rigid surface. Wooden diffusers of cubic and pyramidal shapes were tested in a scale model of a room with dimensions of 0.7x0.4x0.4 m. Sound decay curves were measured at frequencies of 4kHz and 8kHz. Two large walls were covered with a porous absorber, on the third, in certain combinations, the investigated diffusers with a characteristic size of 3.5 cm were placed, the number of which varied from 0 to 29. The idea of the applied method is that the sound decay curve in a room with a non-diffuse sound field depends significantly from the scattering properties of surfaces. The decay curve was measured with different numbers of the diffusers on the test wall, which made it possible to determine the influence of the shape of the diffusers and their number on the value of the normal scattering coefficient. According to the results of the measurements a high scattering ability of cubic elements was revealed in comparison with pyramidal ones.

Highlights

One of the important acoustic characteristics of a surface is the sound scattering coefficient, which is used to determine the acoustic quality of various rooms: concert halls, sound studios, reverberation chambers
The proposed method for measuring the scattering coefficient of sound at normal incidence has been verified in a model experiment
The absorption and scattering coefficients have the same effect on the sound decay curve

Summary

Introduction

One of the important acoustic characteristics of a surface is the sound scattering coefficient, which is used to determine the acoustic quality of various rooms: concert halls, sound studios, reverberation chambers. To determine the scattering properties, there are a number of standardized methods that allow to accurately determine the desired coefficient. These techniques require a large chamber and the creation of a diffuse field [5,6]. The scattering coefficient is determined from the shape of the attenuation curve, given by an exponential-power function and measured in a rectangular room with an uneven distribution of absorption on its walls.

Theoretical basis of the measurement method

Model experiment

Measurement results

Estimated calculation of scattering coefficient

Conclusion