Influence of interaural level differences on the speech recognition masking level difference.

This study was undertaken to determine the effect of interaural level differences on the magnitude of the speech recognition masking level differences obtained from younger and older subjects with normal hearing and from subjects with asymmetrical sensorineural hearing losses. A ten-word subgroup of CID W-1 spondaic words having the largest masking-level differences was used. Masking level differences decreased systematically with increasing interaural level differences for all three groups. At interaural level differences of 36 and 42 dB, the masking level difference persisted for the younger and older normal subjects (1.6 and 1.9 dB, respectively); similar results were obtained from the subjects with hearing losses at a 24-dB interaural level difference. For all subject groups, the S0N0 thresholds were unaffected by changes in the interaural level difference, whereas the S pi N0 thresholds were inversely related to the interaural level difference.