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Title:Multi-Source Noise Reduction Model for Industrial Spaces with Uncertainties in Source Size and Location

By: Panza, M.J.

Date: (2003)

Publication: Proceedings of INCE NOISECON 2003 conference, Cleveland.

Abstract:
A model for the calculation of the noise reduction in large industrial spaces containing many sources is presented. Noise reduction is obtained with a ceiling array of sound absorbers or with a sound absorptive ceiling lining. The floor area contains many sources of various size and location and there is a large ratio of distance between walls to ceiling height. The noise field in the space is composed of three basic parts. The direct sound from the local source to the receiver is determined from an equivalent hemispherical radius for large prismatic source geometry. The direct sound from all other sources is given as an integral over the space. The reverberant sound includes all reverberation from ceiling, floor, and walls. The reverberant field is determined in two ways. One with the Sabine diffuse field formula and one with images approach summing initially over ceiling-floor reflections and then over wall images. The latter approach includes an effect for noise source scattering. An approximate Green’s function for the specularly reflected ceiling-floor reverberation sum is obtained to allow for analytical evaluation of the reverberant field. Results for several source sizes and spacing combinations for the same source field show the procedure’s applicability under conditions of uncertainty. A comparison of the model’s result with two experimental cases shows the utility of the method.