Intelligibility of reverberant speech enhanced by inversion of room response

The effect on speech intelligibility of inverting the impulse response of a small, highly reverberant acoustical space is evaluated. Phonetically balanced (PB) speech material was recorded with a single microphone in an empty room of about 40 m³, with reverberation time of 3 s. The room response was measured using a linear chirp, and various least-squared error inverse filters were designed. Intelligibility of the reverberated and processed speech was measured by quantitative testing with twelve listeners, and by the speech transmission index (STI). Results show improved intelligibility even using very short portions of the room impulse response, with correct responses increasing by 8% using a 93 ms impulse response. Further improvement was noted with increasing filter length. Intelligibility improvements were consistent with two types of subject response tests, but were not reflected in STI values for short filter length