Tomasz R. Letowski
Nancy E. Poch
Penn State Univ., 110 Moore Bldg., University Park, PA 16802
Fifteen subjects, ages 60 to 74 years, participated in a study to assess the role of discard interval length in the understanding of time-compressed speech. Fixed discard intervals previously available in commercial equipment such as the Lexicon Varispeech II have allowed changes in rate of compression only. In the present study, compression rate was held constant at 50% and discard interval length was varied in 20-ms steps from 35 ms, which is within the usual range of discard intervals, to 115 ms. Operationally, this meant that a discard interval of 115 ms resulted in deleting 50% of every 230-ms portion of the text. Performance deteriorated gradually until a critical DI was reached beyond which performance dropped sharply. Results are compared to an earlier study of normal hearing young adult subjects [Poch, presented at ASA (November 1992)] using the same speech test materials and time-compression technique. The difference in performance between the two groups is explained in terms of the effects of aging on speed of auditory processing.