Authors: Iñigo Santamaría Fernández¹, Miriam Marrufo-Pérez², Enrique A. Lopez-Poveda², Joaquin T. Valderrama¹
¹Universidad de Granada; ²University of Salamanca
Background: “Adaptation to noise” is the phenomenon where the detection and recognition of a signal improve when the signal is delayed relative to the onset of background noise. This likely reflects the auditory system’s optimization of neural responses in challenging acoustic environments. While behaviorally well-documented, physiological evidence for this adaptation remains limited. This study investigated whether auditory steady-state responses (ASSRs) serve as a neurophysiological marker of this process.
Method: Eight normal-hearing adults participated in the study. Amplitude modulation (AM) detection thresholds were measured for 40 Hz modulated tones in broadband noise (0 dB SNR) at two temporal positions: 50 ms (early) and 500 ms (late) after noise onset. Neurophysiological data were collected using ASSRs recorded at the same temporal positions with modulation depths of 0 dB and −3 dB.
Results: Behavioral results confirmed significant adaptation, with AM detection thresholds improving from the early to late condition (p = 0.0025). Correspondingly, 40 Hz ASSR amplitudes increased significantly from the early to late position at 0 dB modulation depth (p = 0.0389). However, this effect was not significant at the −3 dB modulation depth, and substantial inter-individual variability was noted in the neural data.
Conclusion: The findings confirm robust behavioral adaptation to noise and suggest that 40 Hz ASSR amplitudes can partially reflect these improvements. While these preliminary results indicate that ASSRs may provide an objective measure of auditory adaptation, the variability observed suggests that larger sample sizes are necessary to establish the reliability of this neurophysiological marker.
