Infrasound exposure is linked to aversive responding, negative appraisal, and elevated salivary cortisol in humans

Introduction Infrasound describes sound wave frequencies below 20 Hz, which are typically imperceptible to humans. Some animals perceive and demonstrate aversion to infrasound, raising concerns about its potential adverse effects as an anthropogenic pollutant. Recent research suggests humans may also respond to infrasound, despite being below the conventional limit of human hearing. This study explored the non-auditory impact of infrasound on human mood and stress responding. Methods Participants ( n = 36) were exposed to calming or unsettling music with infrasound (~18 Hz) present or absent in a 2 × 2 between-subjects design ( calming vs. unsettling , infrasound on vs. off ). Self-report measures were collected immediately post-exposure, and saliva was collected immediately pre-exposure and 20 min post-onset for cortisol assay. Results Participants did not detect infrasound above chance ( p = 0.241). Infrasound was associated with elevated salivary cortisol ( p = 0.022, r rb = 0.390) and higher self-reported irritability ( p = 0.049, η 2 = 0.096), disinterest ( p = 0.044, η 2 = 0.121; p = 0.047, η 2 = 0.118), and sadness appraisal ( p = 0.002, η 2 = 0.253) across both music conditions, with no expectancy effects. Interest, irritability, sadness appraisal, and cortisol were also identified as important predictors of infrasound exposure via random-forest modeling. Discussion Without auditory detection nor expectancy effects, infrasound exposure was linked to elevated cortisol and more negative affective self-reporting. These findings align with previous animal studies and suggest infrasound may be aversive to humans, acting as a potential environmental irritant and contributing to more negative subjective experience.