A laboratory method for measuring normal-incidence scattering coefficients of architectural surfaces

Abstract

Regarding scattering coefficient that represents acoustic scattering capability of architectural surfaces, a reverberation room method for measuring random-incidence values has been standardized in ISO 17497-1, whereas any method has not yet fully established for incidence-angle-dependent values. In this paper, a laboratory measurement method is proposed for normal-incidence scattering coefficients, which will be useful for room acoustics design, particularly assessment of flutter echoes. The measurement is performed in a rectangular room where highly absorbent materials are installed on all sidewalls, and a test sample is mounted on the entire floor. In the quasi-one-dimensional sound field between the floor and ceiling, normal-incidence scattering coefficients of the sample are estimated by measuring the changes of reverberation times with and without the sample. In order to establish the proposed method, the measurement procedure and the test arrangement are examined in 1/4-scale experiments, and finally, it is validated in comparison with theoretical and numerical results.