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Neural measures of spectral modulation detection

Poster Session F - Tuesday, March 10, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom

Siana Lai¹ (), Susan Nittrouer², David Hilton¹, Valerie Shafer¹; ¹CUNY Graduate Center, ²University of Florida

The ability to recognize the shape of the speech spectrum is critical to online speech processing and to the acquisition of language, especially phonological representations. For this reason, there is clinical utility – especially for patients with hearing loss who use cochlear implants – in being able to assess sensitivity to spectral shape. This is usually accomplished by measuring thresholds for spectral modulation depth detection. Behavioral thresholds, however, cannot be obtained before roughly five years of age, well past the critical period of auditory development. Thus, there is urgent need to develop other methods for assessing spectral modulation depth detection. This study examined the potential utility of electrophysiologic measures to do so. Fourteen adults with normal hearing were examined using an electroencephalographic (EEG) measure, the acoustic change complex (ACC), to 600-ms sounds that were unmodulated for the first 300 ms and then were modulated for 300 ms at a rate of 0.5 cycles per octave. Four modulation depths were used: 5 dB, 12 dB, 19 dB, and 26 dB. The first of these has shallow modulation, rarely detected by listeners with normal hearing; depth increased across the stimuli. Results revealed a clear P1-N1 ACC for all stimuli except the one with 5-dB depth, and ACC amplitude increased with increasing modulation depth. These findings match behavioral outcomes, which show 70.7% thresholds close to 7 dB. These findings are promising in suggesting that the ACC to spectral modulation will serve to more accurately quantify sensitivity to spectral structure in acoustic signals.

Topic Area: PERCEPTION & ACTION: Audition