Auditory Research 2026

Spectro-Temporal Modulation Detection in Noise Reveals Hidden Hearing Loss in Young Combat Soldiers

Shai Chordekar Nir Fink
Department of Communication Disorders, Ariel University, Israel

Background/Purpose

Hidden hearing loss (HHL) is a rising diagnostic challenge in combat-exposed populations, where auditory symptoms such as hearing difficulties, tinnitus and hyperacusis persist despite normal audiograms and no clear behavioral markers. Since combat noise may damage cochlear synapses essential for spectro-temporal modulation (STM) in noise, we hypothesized that the Audible Contrast Threshold (ACT), the STM detection in noise task, would differentiate symptomatic, asymptomatic, and control groups, even with similar hearing thresholds.

Methods
123 young adults (Control n=29, Exposed-Asymptomatic n=37, Exposed-Symptomatic n=57) who all met the inclusion criterion of normal hearing sensitivity (pure‑tone thresholds ≤20 dB HL from 0.25–8 kHz) underwent conventional pure-tone audiometry (0.25–8 kHz), extended high-frequency audiometry (EHF, 9–16 kHz), and ACT testing. Combat-exposed participants completed a comprehensive noise exposure history interview and self-report measures, including the Hearing Handicap Inventory for Adults-Screening (HHIA-S) and the Tinnitus and Hearing Survey (THS).

Results
Standard and EHF audiometry showed no significant group differences. However, ACT scores varied significantly, with the Symptomatic group scoring higher (M=1.06 dBnCL) than Controls (M=-0.68 dBnCL; p=.008) and Asymptomatic participants (M=-0.42 dBnCL; p=.035). HHIA-S and THS scores were also elevated in symptomatic individuals. For combat-exposed soldiers, ACT score and blast history independently predicted hearing handicap, explaining 19.2% of HHIA-S variance (p<.001).

Conclusion
In young combat veterans with normal hearing, symptomatic auditory complaints are associated with poorer STM sensitivity and greater self-reported handicap, while standard and EHF audiometry remain unaffected. ACT may serve as a sensitive and clinically feasible marker of HHL, with implications for early identification in combat noise-exposed populations.