Sensitivity to sound-level statistics is crucial for optimal perception, but research has focused mostly on neurophysiological recordings, whereas behavioral evidence is sparse. We use electroencephalography (EEG) and behavioral methods to investigate how sound-level statistics affect neural activity and the detection of near-threshold changes in sound amplitude. We presented noise bursts with sound levels drawn from distributions with either a low or a high modal sound level. One participant group listened to the stimulation while EEG was recorded (Experiment I). A second group performed a behavioral amplitude-modulation detection task (Experiment II). Neural activity depended on sound-level statistical context in two different ways. Consistent with an account positing that the sensitivity of neurons to sound intensity adapts to ambient sound level, responses for higher-intensity bursts were larger in low-mode than high-mode contexts, whereas responses for lower-intensity bursts did not differ between contexts. In contrast, a concurrent slow neural response indicated prediction-error processing: The response was larger for bursts at intensities that deviated from the predicted statistical context compared to those not deviating. Behavioral responses were consistent with prediction-error processing, but not with neural adaptation. Hence, neural activity adapts to sound-level statistics, but fine-tuning of perceptual sensitivity appears to involve neural prediction-error responses.

The effects of transcranial electrical stimulation (tES) approaches have been widely studied for many decades in the motor field, and are well known to have a significant and consistent impact on the rehabilitation of people with motor deficits. Consequently, it can be asked whether tES could also be an effective tool for targeting and modulating plasticity in the sensory field for therapeutic purposes. Specifically, could potentiating sensitivity at the central level with tES help to compensate for sensory loss? The present review examines evidence of the impact of tES on cortical auditory excitability and its corresponding influence on auditory processing, and in particular on hearing rehabilitation. Overall, data strongly suggest that tES approaches can be an effective tool for modulating auditory plasticity. However, its specific impact on auditory processing requires further investigation before it can be considered for therapeutic purposes. Indeed, while it is clear that electrical stimulation has an effect on cortical excitability and overall auditory abilities, the directionality of these effects is puzzling. The knowledge gaps that will need to be filled are discussed.

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Adaptation to sound-level statistics is thought to be crucial for optimal perception, but research has focused on neurophysiological recordings, mostly in non-human mammals. Behavioral evidence for adaptation to sound-level statistics is sparse. Here we use electroencephalography (EEG) and behavioral methods to investigate how the statistics of sound-level distributions affect neural activity in auditory cortex and the detection of near-threshold changes in sound amplitude. We presented noise bursts with sound levels drawn from distributions with either a low (15 dB SL) or a high (45 dB SL) modal sound level.One group of participants listened passively to the stimulation while EEG was recorded (Experiment I).A second participant group performed a behavioral amplitude-modulation detection task (Experiment II). Neural responses to noise bursts and sensitivity to amplitude modulation depended on sound-level statistical context: Consistent with an account positing that the sensitivity of neurons to sound intensity changes with ambient sound level, neural responses and amplitude-modulation sensitivity (d') for noise bursts at moderate intensities were larger for low ambient sound levels compared to high ambient sound levels. Neural activity appears to adapt to sound-level statistics in humans, perhaps fine-tuning perceptual sensitivity to optimize detection of subtle changes in sound amplitude.