The intelligibility of interrupted and temporally altered speech: Effects of context, age, and hearing loss.

Temporal constraints on the perception of interrupted speech were investigated by comparing the intelligibility of speech that was periodically gated (PG) and subsequently either temporally compressed (PGTC) by concatenating remaining speech fragments or temporally expanded (PGTE) by doubling the silent intervals between speech fragments. Experiment 1 examined the effects of PGTC and PGTE at different gating rates (0.5 -16 Hz) on the intelligibility of words and sentences for young normal-hearing adults. In experiment 2, older normal-hearing (ONH) and older hearing-impaired (OHI) adults were tested with sentences only. The results of experiment 1 indicated that sentences were more intelligible than words. In both experiments, PGTC sentences were less intelligible than either PG or PGTE sentences. Compared with PG sentences, the intelligibility of PGTE sentences was significantly reduced by the same amount for ONH and OHI groups. Temporal alterations tended to produce a U-shaped rate-intelligibility function with a dip at 2-4 Hz, indicating that temporal alterations interacted with the duration of speech fragments. The present findings demonstrate that both aging and hearing loss negatively affect the overall intelligibility of interrupted and temporally altered speech. However, a mild-to-moderate hearing loss did not exacerbate the negative effects of temporal alterations associated with aging.