Sound field reconstruction and its application in loudspeaker sound radiation prediction

Yangfan Liu, Purdue University

Abstract

Sound field reconstruction technologies, that is, models of the sound field radiated by some physical sources in different environments, often constitute the key technical component of various acoustics-related engineering applications, such as: sound radiation visualization, sound source identification, audio product evaluation, etc. A new approach was proposed and implemented here to predict the sound radiation of a loudspeaker or other similar audio devices into a room (i.e., reverberant) environment specifically for the purpose of virtual evaluation of a designed product. In the first step of the proposed simulation approach, a free-space sound field model of the physical device is constructed based on anechoic sound field information at a number of locations, either measured or simulated. In the next and final step, the results of the previously generated free-space model are input into a room acoustics model which describes the effect of the room on the sound field, and which allows the sound pressure signals at certain locations in the room to be used for subjective sound quality evaluation. A new model, named the Simple Source Model (SSM), was developed for the free space sound field reconstruction process. Exact definitions of simple sources of different orders were clarified from a mathematical point-of-view, based on which the analytical sound field expressions for simple sources were derived. The method of simple source sound field decomposition was formulated to simplify the form of the model parameter estimation process. Appropriate algorithms were chosen to solve the parameter estimation problem based on research in optimization techniques. For the purpose of room acoustics modeling, an image source model was chosen for its simplicity and because actual listening test rooms are usually of a relatively simple geometry like a rectangular cuboid. Both simulation and experimental results have validated the use of each of the two models involved. A software package was built to perform the whole simulation process and to generate audible signals for product evaluation under different room environments.

Degree

M.S.M.E.

Advisors

Davies, Purdue University.

Subject Area

Mechanical engineering|Acoustics

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