How does ultrasound from mice affect people? - briefly
Ultrasonic signals produced by mice lie above the human audible range and are normally undetectable, producing no measurable physiological effect in everyday exposure. Only at unusually high intensities used experimentally can they induce minor auditory or tissue responses.
How does ultrasound from mice affect people? - in detail
Mouse‑produced ultrasonic vocalizations (USVs) occupy the 30–110 kHz range, well above the upper limit of human hearing (≈20 kHz). The acoustic pressure of these signals is typically 40–70 dB SPL measured at a distance of 10 cm from the animal, decreasing rapidly with distance due to spherical spreading and atmospheric attenuation. Consequently, direct auditory perception by people in ordinary settings is unlikely.
Physiological interaction pathways that could convey effects despite inaudibility include:
- Bone‑conduction transmission: High‑frequency vibrations can travel through the skull, stimulating cochlear structures indirectly. Experimental data show that bone‑conducted ultrasound above 60 kHz can elicit auditory brainstem responses in humans at intensities exceeding 100 dB SPL, a level far greater than that emitted by laboratory mice.
- Somatosensory activation: Skin mechanoreceptors respond to vibration frequencies up to 500 Hz; ultrasounds above 20 kHz are generally ineffective, making direct tactile impact from mouse USVs negligible.
- Neuro‑endocrine modulation: No peer‑reviewed studies have demonstrated hormonal or autonomic changes in humans attributable to exposure to mouse ultrasonic calls at ambient concentrations.
Safety standards set by occupational health agencies (e.g., IEC 60601‑2‑33) define the permissible exposure limit for ultrasound at 115 dB SPL for frequencies up to 100 kHz. Measured mouse USV levels fall well below this threshold, indicating minimal risk under normal laboratory or household conditions.
Research employing controlled exposure chambers has examined potential behavioral effects. In one double‑blind protocol, participants exposed to recorded mouse USVs at 80 dB SPL for 30 minutes reported no significant changes in mood, reaction time, or heart‑rate variability compared to sham exposure. Functional MRI studies have not identified activation of auditory cortices during such sub‑threshold exposure.
In summary, the acoustic power and frequency range of mouse ultrasonic vocalizations are insufficient to produce audible perception or measurable physiological responses in humans under typical exposure scenarios. Only artificial amplification to hazardous levels could pose a health concern, a circumstance not encountered outside specialized experimental setups.