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Objective: Recent studies in rodents show that noise exposure may cause permanent damage to inner hair cell synapses, even when hearing thresholds return to their baseline (Fernandez et al., 2015; Liberman et al., 2015). Emerging evidence indicates that similar damage may occur in humans (Liberman et al., 2016), and is known in the literature as cochlear synaptopathy (CS) or hidden hearing loss. CS would likely cause functional deficits in temporal coding and speech-in-noise (Furman, Kujawa & Liberman, 2013; Kumar et al., 2012). The objective of the current research was to compare the speech-in-noise performance of an at-risk group of student musicians to a control group of individuals with limited noise exposure. Method: The experimental group consisted of 20 student musicians (MAGE = 22.7, SD = 3, range =18-28). The control group was comprised of 22 students with normal hearing and limited noise exposure (MAGE = 21.9, SD = 2.5, range =18-27). Previous noise exposure was estimated using the Noise Exposure Structured Interview (NESI; Guest et al., 2018). The hearing-in-noise test (HINT; Nillson et al., 1994) and the random gap-in-noise test (RGDT; Keith, 2000) were administered to assess temporal and speech-in-noise perception abilities. A Bayesian multilevel linear model was used to investigate differences in HINT scores between groups and conditions. Results: The musician group showed higher estimated lifetime exposure than the control group. Differences were found between conditions of the HINT, but not between groups. No association was found between HINT-ITD and estimated lifetime noise exposure. Discussion: It is possible that the population studied did not have sufficient noise exposure to exhibit difficulties processing temporal stimuli. Given the current literature on CS in humans, strict inclusion criteria, broad research protocols and interdisciplinary collaborations are warranted. Future studies should focus on finding behavioral tests with good sensitivity and specificity to reliably diagnose CS in humans in older musicians.

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Cochlear implants are generally considered the most successful of all sensory neural prostheses currently in use (Wilson and Dorman, 2008). Investigation of auditory perception with cochlear implants is important for developing effective and evidence-based approaches for intervention and management of profound hearing loss. Various phenomena of auditory perception have begun to be explored with cochlear implant users. However, perception of a phenomenon that allows listeners to perceptually restore the continuity of sounds that are partially masked or interrupted by other sounds (“auditory induction” or “auditory continuity”) has not yet been investigated in a group of listeners with cochlear implants. In the current study a group of 10 listeners with cochlear implants and 10 control listeners with normal-hearing provided judgments on the continuity of a pure tone signal in the presence of four levels of a narrow-band noise masker. The group of listeners with cochlear implants reported perception of auditory continuity, but did so for lower levels of the masker when compared to the normal-hearing control group. A secondary experiment investigated simultaneous masking in listeners with cochlear implants using the same masker levels used in the continuity experiment. The cochlear implant group displayed effective masking at a lower level than the normal-hearing control group, the same level at which auditory continuity was perceived in the first experiment. The differences observed between the two groups may be attributable to the greater effects of masking resulting from poorer frequency resolution, lack of temporal fine structure information and reduced dynamic range for users of cochlear implants compared with listeners with normal-hearing.

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This study was designed to explore the effects of topic title and simulated high frequency hearing loss on language comprehension by normal, healthy adults. Thirty-two adult participants with no history of cognitive deficits participated in this study. Each participant listened to four different passages in four different conditions. The four conditions were: (1) title with normal hearing, (2) title with simulated high frequency hearing loss, (3) no title with normal hearing and (4) no title with simulated high frequency hearing loss. Passages were presented segment-by-segment using the auditory moving window technique; most segments were short sentences or clauses. Participants listened to each segment at their own pace by pressing a key. Pause times between segments and overall listening time were recorded for each passage. After listening to each passage, participants were asked to recall out loud what they understood and remembered from the passage. Recall was transcribed and percentages of recalled propositions were calculated. In order to observe changes in processing across a passage, mean pause duration values were also compared across passage position (beginning, middle and end of a passage). The results showed that topic titles facilitated listening comprehension, as shown through better recall performance and reduced processing time. The knowledge of topic titles also reduced the time required for processing information at the beginning of the passage, showing that the knowledge of topic titles facilitates the building of mental representations. The simulated high frequency hearing loss condition did not prove to consistently tax working memory resources during language comprehension. The findings also provided evidence about the relationship between working memory ability and recall performance. Overall, these findings are consistent with the predictions of current language comprehension models.

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