Intelligibility of time-expanded speech with normally hearing and elderly subjects

The effects of time-expanded monosyllabic words (NU-6) on the auditory discrimination performance of 15 young adults with normal hearing and 20 elderly subjects were studied. Three conditions of time expansion, 30, 60 and 100%, plus a 0% control condition, were presented at four sensation levels (8, 16, 24 and 32 dB). For the normally hearing subjects, auditory discrimination performance at all ratios of time expansion was equal to the 0% condition. Results for the elderly subjects indicated intelligibility was inversely related to time expansion at the 30 and 60% conditions. However, at the 100% condition, speech intelligibility improved over the 60% condition at 8 and 16 dB sensation level. At 24 and 32 dB sensation level, performance at 100% was equal to the 60% condition. With the normal and elderly subjects, ear and list effects were minimal. The results are discussed in terms of the clinical value of this procedure and in light of literature that reviews the performance of subjects on tests employing various temporally altered stimuli.