Paralanguage as a tool for shaping stress response in Listeners: Multimodal physiological sensing study.

Background: Sound is a powerful cue that can influence emotional and physiological states. While musical sounds have been widely studied for their stress-reducing effects, less attention has been given to the role of paralanguage. This study investigates whether a soothing vocal intonation beyond its semantic content can facilitate stress recovery by modulating neurophysiological and biochemical stress markers. Methods: Thirty-five participants underwent a standardized stress induction task before being exposed to one of three conditions: a soothing voice narration, a robotic voice narration, or silence. Prefrontal cortex (PFC) hemodynamic activity was recorded using functional near-infrared spectroscopy (fNIRS), while stress biomarkers, including salivary cortisol and electrodermal activity (EDA), were measured at multiple time points. The Laterality Index Response (LIR) was computed to assess stress-related cortical asymmetry. Results: Stress induction significantly increased cortisol levels, EDA, and right-lateralized PFC activation across all groups. During the recovery phase, the soothing voice group demonstrated a significantly faster cortisol reduction compared to both control groups. fNIRS data revealed distinct PFC hemodynamic patterns, with the soothing voice condition shifting activation toward Brodmann areas 45 and 9. However, EDA recovery patterns did not differ significantly across groups. Conclusion: These findings highlight the potential of paralanguage, specifically soothing voice intonation, in accelerating physiological stress recovery. The observed modulation of cortisol and PFC activity suggests that auditory interventions incorporating emotional prosody could enhance stress regulation strategies. Future research should explore individual differences in response to paralanguage-based interventions and their broader clinical applications.