RT Journal Article
SR Electronic
T1 Deciphering Compromised Speech-in-Noise Intelligibility in Older Listeners: The Role of Cochlear Synaptopathy
JF eneuro
JO eNeuro
FD Society for Neuroscience
SP ENEURO.0182-24.2024
DO 10.1523/ENEURO.0182-24.2024
VO 12
IS 2
A1 Garrett, Markus
A1 Vasilkov, Viacheslav
A1 Mauermann, Manfred
A1 Devolder, Pauline
A1 Wilson, John L.
A1 Gonzales, Leslie
A1 Henry, Kenneth S.
A1 Verhulst, Sarah
YR 2025
UL http://www.eneuro.org/content/12/2/ENEURO.0182-24.2024.abstract
AB Speech intelligibility declines with age and sensorineural hearing damage (SNHL). However, it remains unclear whether cochlear synaptopathy (CS), a recently discovered form of SNHL, significantly contributes to this issue. CS refers to damaged auditory-nerve synapses that innervate the inner hair cells and there is currently no go-to diagnostic test available. Furthermore, age-related hearing damage can comprise various aspects (e.g., hair cell damage, CS) that each can play a role in impaired sound perception. To explore the link between cochlear damage and speech intelligibility deficits, this study examines the role of CS for word recognition among older listeners. We first validated an envelope-following response (EFR) marker for CS using a Budgerigar model. We then applied this marker in human experiments, while restricting the speech material’s frequency content to ensure that both the EFR and the behavioral tasks engaged similar cochlear frequency regions. Following this approach, we identified the relative contribution of hearing sensitivity and CS to speech intelligibility in two age-matched (65-year-old) groups with clinically normal (n = 15, 8 females) or impaired audiograms (n = 13, 8 females). Compared to a young normal-hearing control group (n = 13, 7 females), the older groups demonstrated lower EFR responses and impaired speech reception thresholds. We conclude that age-related CS reduces supra-threshold temporal envelope coding with subsequent speech coding deficits in noise that cannot be explained based on hearing sensitivity alone.