Simulated vs real reverberation in intelligibility testing

Abstract

Speech intelligibility was tested in various reverberation conditions for normal-hearing subjects. Simulated reverberation was recorded as five echoes following the primary signal (Modified Rhyme Test). These five echoes were distributed over periods of time of 100, 200, or 300 msec. The amplitude of each echo was 6 dB lower than the preceding one resulting in a 30-dB level difference over the total time. Therefore the recordings simulated reverberation times T of 0.2, 0.4, and 0.6 sec (where T is the time for a 60-dB drop). The test was reproduced in a sound-treated room. The comparison of the data for simulated reverberation with previously obtained data for real reverberation indicates that the artificial reverberation did not reduce intelligibility, in the range of parameters tested, while the real reverberation reduced intelligibility about 15%. The difference may be due to the lack of fine structure of multiple reflections in the simulated signal. [Supported by NIH NISND grant.]