Speech intelligibility improvement in rooms using microphone arrays.

Microphones arrays reduce the effects of reverberation and background noise as compared to a single microphone. The resulting improvement in speech intelligibility in rooms is investigated here, following the approach discussed by Houtgast et al. [Acustica 46, 60–72 (1980)]. Room characteristics (volume, reverberation time), the background noise spectrum, and the source‐receiver separation are used to compute a modulation transfer function. This function is input into the procedure described in IEC standard 60268‐16(2003) to arrive at an objective measure of speech intelligibility, the speech transmission index (STI). Doing this for both omnidirectional and microphone array receivers, the improvement in intelligibility is determined. The signal source has the spectral shape of a human talker, as given in the IEC standard; the background noise spectrum is based on measurements made in a restaurant. The benefit of using microphone arrays is discussed for various conditions.