Binaural Hearing of Speech for Aided and Unaided Conditions

Differences in speech intelligibility and identification between binaural, monaural near ear, and monaural far ear conditions were studied in sound field conditions. Scores from listeners with normal hearing and with sensorineural losses were evalated in sound field conditions (unaided) and under conditions of hearing aid amplification (aided). For both conditions listeners with sensorineural hearing loss obtained a binaural advantage similar to that found for normal listeners. The binaural advantage could be demonstrated only when the primary and/or competing signal sources were located at an azimuth which resulted in interaural time differences for at least one of the signals. When the signals arrived simultaneously at the ears from the same loudspeaker, no binaural advantage was obtained. Differences in intelligibility and identification scores between monaural near ear and far ear conditions (6.0 dB) were almost twice as large as those found between binaural listening and monaural near ear listening (3.3 dB).