Acoustic characterization of facings with periodic profiles used in industrial rooms

Facings in industrial rooms can have periodic profiles. Various methods for the acoustic characterization of those kind of facings are presented in this work. The waveguides method, is well adapted to the geometries usually met in industrial rooms. According to this method, the profile geometry is simplified using elementary rectangular volumes. The acoustic field in the profile interstices can then be expressed as the superposition of waveguide modes. Numerical simulations of the waveguides method were realized, and physical phenomena associated with the sound reflection on periodic facings were observed. The waveguides method was also numerically compared with other existing methods. A generalization of this method have been proposed to extend its applicability to "twice-periodic" facings. Free field measurements were also carried out. The agreement between numerical and experimental results proves that the waveguides method is valid. This method showed that periodic structures act as acoustic diffusers and that they may also amplify their materials's absorption.