The Effect of Hearing Loss on the P300 Auditory-Evoked Potential as a Measure of Listening Effort

Objectives: Individuals with hearing loss often experience increased listening effort. While the P300 component has been established as a potential physiological marker of listening effort, existing research has largely focused on individuals with normal hearing. This study aims to address this gap by examining the impact of hearing loss on the P300 response, assessing its potential as an indicator of cognitive engagement associated with listening effort in adults with and without hearing loss. Design: Fifty-two middle-aged and older adults with normal hearing and 52 with hearing loss participated in the study (mean age for the total group: 67.38 years, SD: 7.71 years, range: 45 to 80 years). The groups were matched in age, sex, and educational level. The P300 was recorded at Fz, Cz, and Pz referenced to the nose using a two-stimulus oddball paradigm with Flemish monosyllabic numbers. This paradigm was conducted under two quiet conditions (65 and 69 dB SPL) and two noise conditions (0 dB signal to noise ratio [SNR] and +4 dB SNR). Within the deviant waveform, N1 amplitude and latency were analyzed as indices of cortical detection, alongside P300 amplitude, latency, and N1-P300 interpeak interval, which served as measures of cognitive engagement associated with listening effort. Reaction time to respond to the deviant stimuli was used as a behavioral measurement of listening effort. To examine the effects of listening condition and hearing group on these outcome measures, linear mixed-effects models were used for the two quiet and two noise listening conditions, separately. Results: Linear mixed-effects models for listening conditions in quiet revealed significantly larger N1—but not P300—amplitudes, as well as prolonged P300 latencies and N1-P300 interpeak intervals in participants with hearing loss compared to those without hearing loss. Under noise conditions, N1—but not P300—amplitudes were smaller at 0 dB SNR. At 0 dB SNR, both N1 and P300 latencies were significantly prolonged. The hearing loss group also showed longer P300 latencies. To account for delays in early cortical detection, the N1-P300 interpeak intervals were calculated, revealing a significant effect of hearing loss but not listening condition. In addition, reaction times were significantly slower at 0 dB SNR compared with +4 dB SNR in both hearing groups. Conclusions: In quiet, prolonged P300 latencies and N1-P300 interpeak intervals in individuals with hearing loss suggest increased cognitive demands compared with normal-hearing peers. In noise, P300 latencies were affected by both listening condition and hearing loss; however, after accounting for delays in early cortical detection, only hearing loss remained significant—underscoring the impact of hearing loss on higher-order auditory processing. These findings highlight the potential of the P300, particularly the N1-P300 interpeak interval, as physiological markers of cognitive engagement associated with listening effort.