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Influence of the absorption coefficient and material boundaries distribution on the acoustic pressure in the room with rigid walls
Author(s) -
Blazejewski Andrzej,
Krzyzynski Tomasz
Publication year - 2008
Publication title -
pamm
Language(s) - English
Resource type - Journals
ISSN - 1617-7061
DOI - 10.1002/pamm.200810673
Subject(s) - eigenfunction , modal , amplitude , acoustics , harmonic , mathematical analysis , sound pressure , absorption (acoustics) , function (biology) , distribution (mathematics) , acoustic impedance , modal analysis , mathematics , attenuation coefficient , physics , distribution function , materials science , vibration , thermodynamics , optics , quantum mechanics , composite material , eigenvalues and eigenvectors , evolutionary biology , biology , ultrasonic sensor
In the paper a problem of distribution of an acoustic absorption materials on room's boundaries has been presented. A room with a harmonic sound source inside has been considered. A pressure distribution was described using modal analysis assumptions. Usually, most of real rooms have enough high boundaries' impedance (absorption coefficient), therefore the modal coupling can be neglected. Hence, pressure can be represented by a sum over a set of room's eigenfunctions and time components i.e. the modal amplitudes. Amplitudes are dependent of eigenfrequencies ω n , damping coefficients r n and a source function Q n . Conducting analysis of the modal amplitude function, in relation to ω n and r n , an optimal acoustical damping can be obtained. Taking triple criteria objective function into consideration, absorbtion material optimal distribution on boundaries has been found. In order to find minimum of the objective function genetic algorithm was used. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)