Perception of interrupted speech and the influence of speech materials and memory load were investigated using one or two concurrent square-wave gating functions. Sentences (Experiment 1) and random one-, three-, and five-word sequences (Experiment 2) were interrupted using either a primary gating rate alone (0.5À24 Hz) or a combined primary and faster secondary rate. The secondary rate interrupted only speech left intact after primary gating, reducing the original speech to 25%. In both experiments, intelligibility increased with primary rate, but varied with memory load and speech material (highest for sentences, lowest for five-word sequences). With dual-rate gating of sentences, intelligibility with fast secondary rates was superior to that with single rates and a 25% duty cycle, approaching that of single rates with a 50% duty cycle for some low and high rates. For dual-rate gating of words, the positive effect of fast secondary gating was smaller than for sentences, and the advantage of sentences over word-sequences was not obtained in many dual-rate conditions. These findings suggest that integration of interrupted speech fragments after gating depends on the duration of the gated speech interval and that sufficiently robust acoustic-phonetic word cues are needed to access higher-level contextual sentence information.

How age and hearing loss affect the perception of interrupted speech may vary based on both the physical properties of preserved or obliterated speech fragments and individual listener characteristics. To investigate perceptual processes and interruption parameters influencing intelligibility across interruption rates, participants of different age and hearing status heard sentences interrupted by silence at either a single primary rate (0.5-8 Hz; 25%, 50%, 75% duty cycle) or at an additional concurrent secondary rate (24 Hz; 50% duty cycle). Although age and hearing loss significantly affected intelligibility, the ability to integrate sub-phonemic speech fragments produced by the fast secondary rate was similar in all listener groups. Age and hearing loss interacted with rate with smallest group differences observed at the lowest and highest interruption rates of 0.5 and 24 Hz. Furthermore, intelligibility of dual-rate gated sentences was higher than single-rate gated sentences with the same proportion of retained speech. Correlations of intelligibility of interrupted speech to pure-tone thresholds, age, or measures of working memory and auditory spectro-temporal pattern discrimination were generally low-to-moderate and mostly nonsignificant. These findings demonstrate rate-dependent effects of age and hearing loss on the perception of interrupted speech, suggesting complex interactions of perceptual processes across different time scales.

BACKGROUND AND OBJECTIVES: High bilirubin levels are associated with sensorineural hearing loss (SNHL). However, few large studies of relative and excess risk exist. We sought to quantify the risk of SNHL in newborns who had bilirubin levels at or above American Academy of Pediatrics exchange transfusion thresholds (ETT).

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 (PG TC ) by concatenating remaining speech fragments or temporally expanded (PG TE ) by doubling the silent intervals between speech fragments. Experiment 1 examined the effects of PG TC and PG TE 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 hearingimpaired (OHI) adults were tested with sentences only. The results of experiment 1 indicated that sentences were more intelligible than words. In both experiments, PG TC sentences were less intelligible than either PG or PG TE sentences. Compared with PG sentences, the intelligibility of PG TE 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.

Temporal constraints on the perception of variable-size speech fragments produced by interruption rates between 0.5 and 16 Hz were investigated by contrasting the intelligibility of gated sentences with and without silent intervals. Concatenation of consecutive speech fragments produced a significant decrease in intelligibility at 2 and 4 Hz, while having little effect at lower and higher rates. Consistent with previous studies, these findings indicate that (1) syllable-sized intervals associated with intermediate-rate interruptions are more susceptible to temporal distortions than the longer word-size or shorter phoneme-size intervals and (2) suggest qualitative differences in underlying perceptual processes at different rates.