The diffuse sound field according to literature: similarities and differences

De Carvalho, A. C. F. Postgraduate Program in Mechanical and Materials Engineering, Universidade Tecnológica Federal do Paraná, Curitiba, PR, Brasil, augustoc@alunos.utfpr.edu.br

Gomes, M. H. A. Academic Department of Mechanics, Universidade Tecnológica Federal do Paraná, Curitiba, PR, Brasil, marciogomes@utfpr.edu.br

Sant’Ana, L. H. Postgraduate Program in Civil Engineering, Universidade Tecnológica Federal do Paraná, Curitiba, PR, Brasil, luis.2014@alunos.utfpr.edu.br

Abstract

Several acoustic measurement procedures are elaborated under the assumption that they happen inside an ideally diffuse sound field. However, the definition of diffuseness may vary between standards for different applications. Also, there has been discussion on the means to verify the degree of diffusion, on the hindrances to generate such field and how to overcome them. Therefore, this paper’s goal is to revise the different definitions of “diffuse sound field” and define the conditions that in which it is reasonable to declare that the field is sufficiently diffuse for practical purposes. For that, there is also a review of diffuseness indicators. The analysis of several studies on the subject reveals that diffuseness is intrinsically related to an uniform sound intensity in all directions and phase directional incoherence. If this characteristic is present in a sufficient large number of points and applied in conjunction with a model that considers the propagation of plane waves, it means that the sound field can be considered as diffuse.

Keywords:

acoustic field

statistical room acoustics

diffuseness

crossover time

crossover frequency.

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