Adult Diagnostic (AD)
Sajana Aryal, PhD
Graduate Research Assistant
University of Texas at Austin
Austin, Texas
Disclosure(s): No financial or nonfinancial relationships to disclose.
The study aimed to investigate the relationship between extended high-frequency hearing sensitivity and the impact of talker sex and spatial cues on auditory stream segregation in normal-hearing adults. The experimental protocol included a comprehensive audiological assessment including standard pure tone audiometry, EHF audiometry, quantification of lifetime noise exposure via the Noise Exposure Structured Interview, and an auditory segregation test. Linear mixed-effects models were used to analyze the effect of age, sex, NESI, standard audiometric frequency thresholds, and EHF thresholds. Preliminary analyses suggest a complex relationship between NESI, EHF, and auditory speech segregation thresholds for both talker sex and spatial conditions.
Summary:
PURPOSE
Nearly 10% of listeners with clinically normal audiograms complain of difficulty understanding speech in noisy environments. These listeners face the most challenge when identifying target speech in the presence of competing talkers, a common environment for listening and communication. The ability to differentiate the fundamental frequency (perceived as voice pitch) of an individual talker is an important cue to identify talker sex in the presence of competing talkers. Likewise, differentiating among binaural cues is closely related to spatial segregation abilities. Emerging evidence suggests that hearing above 8 kHz (termed EHFs; Extended high frequencies) is important for speech clarity, sound localization, and speech-in-noise recognition, in addition to identifying talker-sex and/or spatial cues. Thus, it is possible that in normal hearing (up to 8 kHz) listeners with speech-in-noise deficits, poor hearing sensitivity in the EHF range could be related to auditory stream segregation. Converging evidence also suggests that EHF hearing is highly sensitive to damage from noise exposure. The primary objective of the study was to examine the relationship between hearing sensitivity in the EHF range, talker sex, and spatial cues for auditory stream segregation in young, normal-hearing adults. A secondary goal was to examine the effect of routine noise exposure on EHF hearing sensitivity. Elucidating the relationship between these variables can help determine the mechanisms underlying listening-in-noise complaints in individuals that have clinically normal audiograms. Further, examining the impact of noise exposure on EHF hearing is of paramount significance within audiology and occupational health domains, as EHF hearing loss can be an early indicator of noise-induced hearing loss.
METHODS
Fifteen normal-hearing adults (mean age = 22 years; 11 females) have participated in the study. Additional participants are in the process of enrollment. The experimental protocol included (1) a comprehensive audiological assessment including standard pure tone audiometry (0.25-8 kHz) and extended high frequency audiometry (10, 12.5, and 16 kHz), (2) quantification of lifetime noise exposure via the Noise Exposure Structured Interview (NESI), and (3) an auditory segregation test measured via modified coordinate response measure task, where spatial location and talker sex of the target and masker speech were systematically varied in four conditions.
The effect of age, sex, NESI, hearing thresholds at standard audiometric frequencies, and EHFs were examined using linear mixed-effects models. The response variables were SRTs from four conditions and the release from masking for talker-sex and spatial segregation conditions. A mediation analysis was performed to analyze the effect of EHF on the relationship between NESI hearing and response variables.
RESULT
Preliminary analyses suggest a complex relationship between NESI, EHF, and SRTs for both talker-sex and spatial conditions. In addition, an interaction effect of NESI and EHF with the release from masking for talker-sex and spatial listening conditions was observed. These preliminary results were adjusted for age and sex effects and will be supplemented with additional data collection.
DISCUSSION
Extended high-frequency hearing may play an important role in auditory stream segregation and could provide one explanation for listening deficits in listeners with normal audiograms.