Binaural masking level difference for speech signals in noise.

This study investigates the binaural masking level difference in both detection and recognition of speech embedded in noise when the signal is phase-shifted 180 degrees between the left and the right ear. Swedish spondaic words masked by noise werc presented binaurally to 10 normally hearing subjects. The results are presented in terms of speech detection threshold, speech recognition threshold, a psychometric function of speech recognition versus signal-to-noise ratio, and speech intelligibility as a function of binaural intelligibility level difference. Both speech detection threshold and speech intelligibility improved when the speech signal was phase-shifted 180 degrees. The binaural intelligibility level difference ranged from 5.7 to 7.7 dB.