title: Amplitude-modulation detection by recreational-noise-exposed humans with near-normal hearing thresholds and its medium-term progression.
abstract: Noise exposure can affect the functioning of cochlear inner and outer hair cells (IHC/OHC), leading to multiple perceptual changes. This work explored possible changes in detection of amplitude modulation (AM) at three Sensation Levels (SL) for carrier frequencies of 3, 4 and 6 kHz. There were two groups of participants, aged 19 to 24 (Young) and 26 to 35 (Older) years. All had near-normal audiometric thresholds. Participants self-assessed exposure to high-level noise in recreational settings. Each group was sub-grouped into low-noise (LN) or high-noise (HN) exposure. AM detection thresholds were worse for the HN than for the LN sub-group at the lowest SL, for the males only of the Young group and for both genders for the Older group, despite no significant difference in absolute threshold at 3 and 4 kHz between sub-groups. AM detection at the lowest SL, at both 3 and 4 kHz, generally improved with increasing age and increasing absolute threshold, consistent with a recruitment-like process. However, poorer AM detection was correlated with increasing exposure at 3 kHz in the Older group. It is suggested that high-level noise exposure produces both IHC- and OHC-related damage, the balance between the two varying across frequency. However, the use of AM detection offers poor sensitivity as a measure of the effects.
authors.affiliation: Audiology and Deafness Group, School of Psychological Sciences, University of Manchester, Manchester, M13 9PL, UK; Auditory Perception Group, Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, UK. Electronic address: michael.stone@manchester.ac.uk.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Stone
authors.affiliation: Auditory Perception Group, Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, UK.
authors.forename: Brian C J
authors.initials: BC
authors.lastname: Moore
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D001299:Audiometry; D001309:Auditory Threshold; D003051:Cochlea / Q000502:physiology; D005260:Female; D006198:Hair Cells, Auditory / Q000502:physiology*; D006309:Hearing; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis; D006320:Hearing Tests; D006801:Humans; D008297:Male; D009622:Noise; D012737:Sex Factors; D011795:Surveys and Questionnaires; D013997:Time Factors; D055815:Young Adult