Relationship between two measures of aided binaural advantage.

The relationship between aided binaural squelch measured using a conventional paradigm and binaural squelch inferred from the ability to detect an intelligibility difference between binaural and pseudobinaural stimuli (presumably utilizing interaural time and intensity cues) was investigated. The conventional measures of aided binaural squelch included the NU-6 monosyllables and the high-predictability sentences from the revised SPIN test. For each measure, binaural squelch was derived by comparing the binaural intelligibility of speech-in-babble with corresponding monaural scores. Subjects were also asked to select the more intelligible hearing-aid-processed speech sample when presented with a paired-comparison task in which each pair consisted of a binaural and a pseudobinaural stimulus. Ability to choose the binaural stimulus as most intelligible was considered to be evidence of binaural squelch ability. Although the hearing-impaired subjects demonstrated typical binaural squelch for the conventional speech tests, they were usually unable to distinguish between the binaural/pseudobinaural pairs. These results suggest that (a) binaural squelch measured using conventional procedures does not necessarily quantify the listener's ability to profit from interaural differences, and (b) many hearing-impaired individuals may be unable to utilize interaural differences to enhance speech intelligibility in noise.