Somatosensory influence on auditory cortical potentials for self-generated sounds during a loudness discrimination task.

Auditory attenuation of self-generated sounds is often attributed to motor prediction based on motor commands. Our previous study (Endo et al., 2025) demonstrated that somatosensory inputs also interact with auditory processing during a rhythmic finger tapping sound generation task. The current study further investigated the mechanism underlying this auditory-somatosensory interaction. We recorded auditory event-related potentials (ERPs) during a loudness discrimination task involving self-generated sounds, which were generated by discrete finger tapping movements pressing on a virtual object rendered by a haptic robotic device. Somatosensory input was manipulated by unpredictably varying the stiffness of the virtual object between low and high levels. In each trial, participants judged whether the comparison sound stimulus was louder than the standard stimulus, which was always associated with a discrete finger tapping movement. Also, ERPs elicited by the standard stimulus were compared across somatosensory conditions. At the behavioral level, no significant modulation of loudness perception was observed across somatosensory conditions. In the ERP responses, we did not observe the typical auditory attenuation effects in the N1 and P2 components that are commonly reported for self-generated sounds. In contrast, ERP activity after 300 ms was significantly modulated by somatosensory condition, consistent with our previous findings. Unlike our previous rhythmic finger tapping study, no somatosensory modulation was found in the auditory N1 component. These results indicate that somatosensory inputs consistently interact with the auditory processing of self-generated sounds, while the characteristics of this interaction were found to depend on task context.