Rediscovery of a seventh sense: humans produce, perceive, and process ultrasound.

Introduction: We present novel evidence that humans are capable of producing, perceiving, and cortically processing ultrasound (US), extending the recognized limits of human auditory function. This previously unacknowledged sensory ability was identified in an expert practitioner of the traditional Chinese health exercise "The Six Healing Sounds. Methods and results: High-resolution recordings demonstrated deliberate vocal emissions reaching up to 35 kHz, with nearly one third of the acoustic energy residing in the ultrasonic range. Magnetoencephalography (MEG) revealed a distinct cortical response to these US components, characterized by an additional early N1 peak at 87 ms in the left auditory cortex-about 20-25 ms earlier than the conventional N1 response. Importantly, this US-specific component was entirely absent in a large cohort of 202 vocalists comprising 23 Chinese and 172 European trained singers and furthermore 7 experienced 'Healing Sound' singers, none of whom produced or perceived vocal US. Beyond cortical physiology, psychophysical testing demonstrated a unique perceptual strategy in the qigong practitioner: at very high frequencies his pitch perception shifted from spectral to fundamental mode, enabling him to reconstruct coherent auditory objects even when ultrasonic components were only weakly present. Discussion: This finding may reflect an exceptional adaptive neuroplastic mechanism integrating US into auditory and regulatory brain networks, akin to functional reorganizations observed in professional musicians. Taken together, these results provide the first demonstration in a human case study of intentional ultrasonic vocalization combined with cortical US processing in a human. The discovery not only challenges the traditional definition of auditory limits but also opens promising perspectives for the role of US in internal communication, vegetative regulation, and clinical neuromodulation. Low-intensity US stimulation may thus represent a novel therapeutic avenue for auditory and neurological disorders.