The Intelligibility of Interrupted Speech: Cochlear Implant Users and Normal Hearing Listeners

Abstract

Compared with normal-hearing listeners, cochlear implant (CI) users display a loss of intelligibility of speech interrupted by silence or noise, possibly due to reduced ability to integrate and restore speech glimpses across silence or noise intervals. The present study was conducted to establish the extent of the deficit typical CI users have in understanding interrupted high-context sentences as a function of a range of interruption rates (1.5 to 24 Hz) and duty cycles (50 and 75 %). Further, factors such as reduced signal quality of CI signal transmission and advanced age, as well as potentially lower speech intelligibility of CI users even in the lack of interruption manipulation, were explored by presenting young, as well as age-matched, normal-hearing (NH) listeners with full-spectrum and vocoded speech (eight-channel and speech intelligibility baseline performance matched). While the actual CI users had more difficulties in understanding interrupted speech and taking advantage of faster interruption rates and increased duty cycle than the eight-channel noise-band vocoded listeners, their performance was similar to the matched noise-band vocoded listeners. These results suggest that while loss of spectro-temporal resolution indeed plays an important role in reduced intelligibility of interrupted speech, these factors alone cannot entirely explain the deficit. Other factors associated with real CIs, such as aging or failure in transmission of essential speech cues, seem to additionally contribute to poor intelligibility of interrupted speech.

Verbal working memory and inhibition‐concentration in adults with cochlear implants

“…The study was motivated by previous findings suggesting that WM declines underlie variability in outcomes in adults with CIs. For example, Bhargava, Gaudrain, and Başkent identified poorer intelligibility of interrupted meaningful sentences in adult CI users than in NH listeners, and attributed poorer performance at least in part to older age in the CI users . Although not specifically mentioning WM, the authors of that study suggest a general slowing of cognitive processing in older CI users may have deleteriously affected their use of top‐down mechanisms during speech recognition.…”

“…For example, Bhargava, Gaudrain, and Başkent identified poorer intelligibility of interrupted meaningful sentences in adult CI users than in NH listeners, and attributed poorer performance at least in part to older age in the CI users. 28 Although not specifically mentioning WM, the authors of that study suggest a general slowing of cognitive processing in older CI users may have deleteriously affected their use of top-down mechanisms during speech recognition. A study by Tao et al found relations between auditory measures of verbal WM (using forward and reverse digit span) and sentence recognition in quiet and in speech- shaped noise; however, findings of that study were confounded by the issue of audibility during the WM tasks.…”

Cognitive Compensation of Speech Perception With Hearing Impairment, Cochlear Implants, and Aging

“…When spectral resolution is high (16 bands), where the restoration benefit is present, or low (4 bands), where the restoration benefit is absent, presence or absence of F0 does not seem to matter (overlap of red and black circles). However, in the mid ranges of spectral resolution (6 bands), the range that yields intelligibility performance most similar to actual CI users (e.g., Bhargava et al., 2016 ; Friesen et al., 2001 ), presence or absence of F0 seems to play a significant role in restoration benefit (larger benefit for red than black circles). Hence, these simulation results show that the interaction between bottom-up cues and the cognitive compensation is complex, and the exact amount and type of information provided by the hearing device can affect how much top-down restoration may occur.…”

The role of envelope periodicity in the perception of masked speech with simulated and real cochlear implants

“…Secondly, and perhaps more importantly, it has been shown (Bhargava et al, 2016) that similar intelligibility levels of interrupted speech with simulated and actual CIs require the age as well as the performance with uninterrupted speech to be matched across groups, possibly because age-related declines affect the ability of older listeners to integrate the individual speech segments.…”