What do rats hear? - briefly
Rats detect sounds from roughly 200 Hz up to about 80–100 kHz, far beyond the human audible range. Their hearing is especially acute in the ultrasonic band, which they use for communication and environmental cues.
What do rats hear? - in detail
Rats possess a highly developed auditory system that detects a broad spectrum of sound frequencies. Their cochlea is tuned to frequencies between approximately 250 Hz and 80 kHz, with peak sensitivity around 12–16 kHz. This range extends well into the ultrasonic domain, allowing detection of sounds inaudible to humans.
The auditory threshold varies across the spectrum. At 12 kHz, rats can perceive sounds as faint as 10 dB SPL, while sensitivity declines at lower frequencies, requiring around 30 dB SPL for detection near 2 kHz. Ultrasonic thresholds remain low; at 50 kHz, detection occurs near 20 dB SPL.
Key functional aspects include:
- Communication: Ultrasonic vocalizations (USVs) between 20 kHz and 80 kHz convey social information such as distress, mating readiness, and territorial signals.
- Predator avoidance: High‑frequency cues from aerial or terrestrial predators trigger rapid escape responses.
- Environmental awareness: Rats respond to low‑frequency vibrations generated by footsteps, machinery, or moving objects, facilitating navigation and foraging.
The peripheral anatomy contributes to this performance. The external ear forms a funnel that concentrates sound toward the tympanic membrane. The middle ear contains a three‑ossicle chain (malleus, incus, stapes) that amplifies vibrations. The inner ear’s basilar membrane exhibits a tonotopic organization, with basal regions responding to high frequencies and apical regions to low frequencies.
Neural processing occurs in the cochlear nucleus, inferior colliculus, and auditory cortex. Electrophysiological studies reveal precise temporal coding, enabling rats to discriminate rapid changes in ultrasonic calls. Behavioral experiments demonstrate that rats can localize sound sources within a few centimeters, using interaural time and intensity differences.
Laboratory assessments employ methods such as auditory brainstem response (ABR) recordings, operant conditioning tasks, and playback of recorded USVs. These techniques confirm that rats maintain acute sensitivity throughout their hearing range and rely on auditory cues for social interaction, predator detection, and environmental exploration.