Measurement of Surface Reflection Properties. Concepts and Uncertainties

In this thesis, acoustic measurement techniques related to the absorbing as well as the scattering properties of architectural surfaces are investigated. The research is divided into two parts: the first part consists of determining the most relevant causes of uncertainty for the standardized measurement methods of random-incidence absorption and scattering coefficients. A method is developed to determine the necessary minimum number of source-receiver combinations in the reverberation chamber to ensure a specified precision of the absorption or scattering coefficient. The second part of the thesis focuses on a hemispherical microphone array and signal processing steps related to the measurement of angle-dependent reflection properties. Measurements show that the array setup can be used to obtain the angle-dependent absorbing properties of samples with few source positions. With the help of array signal processing methods, the setup can also be used to determine the directional diffusion and scattering coefficient of small samples, yielding the same result as established far-field methods.