Vivi Tran1, Louise Plougheld1, Pushkar Deshpande1,2, Tobias Neher1,2
Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
2Research Unit for ORL – Head & Neck Surgery and Audiology, Odense University Hospital, Odense, Denmark; University of Southern Denmark

Electrophysiological measurements can be used for investigating how speech sounds are processed in the brain. This can provide insights into the cortical processes underlying speech perception, which may improve hearing rehabilitation. The aim of the current study was to investigate how speech sounds are processed by normal-hearing listeners and experienced hearing-aid users. Fifteen young normal-hearing listeners and eight experienced hearing-aid users participated. The hearing-aid users were bilaterally fitted with Widex Evoke Fusion 440 devices according to NAL-NL2 target gains. N100, P300, N400 and Late Positive Complex (LPC) responses were elicited using the digit stimuli from the DANTALE-I material. All measurements were carried out in the presence of speech-shaped noise at 67 dB SPL. The N100 and P300 responses were elicited using an active oddball paradigm. The N400 and LPC responses were elicited using an ‘arithmetic’ paradigm based on congruent and incongruent digit sequences. While the N100, P300 and LPC latencies were comparable with literature data, the N400 response occurred approx. 100 ms earlier than in studies based on ‘linguistic’ paradigms. No group differences in terms of amplitudes or latencies of the different EEG components were found. Follow-up studies with larger and more homogeneous groups of hearing-aid users will facilitate a better understanding of how speech sounds are processed in the brains of such listeners. Performing such measurements before and after hearing-aid intervention will provide prognostic indicators with respect to treatment outcome.