How does a rat speak, can it be heard? - briefly
Rats produce ultrasonic vocalizations for social signaling, which exceed the human hearing range, and also emit audible squeaks during distress or aggression. Consequently, most of their communication cannot be heard by people, though louder, low‑frequency sounds are perceptible.
How does a rat speak, can it be heard? - in detail
Rats generate acoustic signals through a combination of vocal fold vibration and airflow modulation. During exhalation, the laryngeal muscles contract, forcing air through the glottis and creating ultrasonic squeaks that can reach frequencies above 50 kHz. When the animal is stationary, the vocal cords produce lower‑frequency chirps (5–20 kHz) associated with social contexts such as mating or aggression. In addition to vocalizations, rats emit ultrasonic clicks by rapidly opening the jaw, a behavior known as “air‑puff” signaling, which conveys alarm or territorial warning.
Human auditory perception typically caps at 20 kHz, so the high‑frequency components of rat communication remain inaudible without specialized equipment. Standard microphones designed for ultrasonic capture, coupled with a spectrum analyzer, reveal the full range of rat sounds. Recording setups often include a condenser microphone with a flat response up to 100 kHz, preamplifier gain adjusted to 30 dB, and a sampling rate of at least 250 kS/s to avoid aliasing.
Key characteristics of rat acoustic output:
- Frequency bands:
• Ultrasonic squeaks: 30–80 kHz, duration 10–100 ms.
• Low‑frequency chirps: 5–20 kHz, duration 50–200 ms. - Amplitude: Peak sound pressure levels range from 50 to 80 dB SPL measured at 10 cm distance.
- Contextual usage:
- Mating calls: repetitive ultrasonic sequences, increased rate during estrus.
- Aggressive encounters: sharp, broadband bursts with rapid onset.
- Distress signals: irregular, high‑amplitude clicks accompanied by foot‑stomping vibrations.
Behavioral studies demonstrate that rats respond to playback of recorded calls, adjusting locomotion, grooming, and social approach. When playback frequencies fall below the ultrasonic threshold, the same patterns lose efficacy, confirming the reliance on high‑frequency hearing. Consequently, while the sounds are physically present, they escape ordinary human perception and require dedicated ultrasonic recording and playback systems to be observed and analyzed.