Binaural benefit--when and how much?

Subjective ratings of aided hearing ability on a five point scale in ten hypothetical listening situations were obtained from 150 binaural hearing aid users, and from 296 monaural hearing aid users. Ratings of unaided hearing ability in nine of the same situations were obtained from 125 persons with self-defined normal hearing. The results indicated that in situations where signal-to-noise ratio was low, hearing aid users rated their listening much below the performance of normal hearing persons, binaural users indicating no advantage over monaural users. In the other hypothetical situations the binaural users rated their ability higher than did the monaural aid users. In some situations, where the sound was presented from a single source, binaural aid users rated their ability on a par with the normal hearing individuals. Age and hearing loss had small effects on the ratings, but the magnitudes of these effects were considerably less than that attributable to the type of aid provision, that is, whether monaural or binaural. These findings lend support to the benefits of binaural amplification in many listening situations.