ABSTRACT
In optics the spatial modulation transfer function (MTF) has an established position as a measure of the faithfulness with which pictures are transferred. The finding that the MTF can be used to measure the quality of speech transmission in a room raises the question of whether it can be used, too, at the design stage to predict this quality. For the most simple case of a rectangular room the MTF can be computed from the coordinates of a great many virtual sound sources. The chapter shows that the temporal MTF is a valuable basis for determining speech intelligibility in rooms. In this condition, the only disturbing factors are noise, echoes, and reverberation. The spectral MTF can be measured in a way comparable to the case of the temporal MTF, by using so-called comb-filtered noise. Hearing losses manifest themselves not only in an elevation of the threshold for understanding speech in quiet, but also in the presence of noise.
