"Sound" - what is it, definition of the term
Sound is a mechanical disturbance that travels through a material medium as longitudinal pressure waves, defined by parameters such as frequency, amplitude, and timbre; when these oscillations reach a receiver’s auditory apparatus, they are transduced into neural signals that the brain interprets as audible perception.
Detailed information
Rats and mice possess highly sensitive auditory systems that detect frequencies far beyond the upper limit of human hearing. Their cochlear structure includes hair cells tuned to ultrasonic ranges, enabling perception of calls between 20 kHz and 100 kHz. This capability supports social communication, predator avoidance, and environmental navigation.
Key characteristics of their auditory perception:
- Frequency range: 1 kHz – 100 kHz, with peak sensitivity around 40 kHz for mice and 50 kHz for rats.
- Thresholds: detection of acoustic pressure as low as 10 dB SPL in the ultrasonic band.
- Temporal resolution: ability to resolve inter‑pulse intervals as short as 5 ms, facilitating rapid signal processing.
These rodents emit a variety of vocalizations, classified by context:
- Alarm calls – brief, high‑frequency bursts triggered by threat; serve to warn conspecifics.
- Mating songs – complex sequences with modulated frequency sweeps, used during courtship.
- Pup distress cries – ultrasonic squeaks that elicit parental retrieval behavior.
Research applications exploit these acoustic properties. Ultrasonic vocalization recording provides a non‑invasive metric for assessing stress, pain, and social interaction in laboratory settings. Playback experiments reveal behavioral responses to specific call types, informing models of communication disorders. Additionally, auditory evoked potentials measured via electrophysiology map neural pathways from the cochlea to the auditory cortex.
Technological tools for studying rodent acoustic behavior include:
- High‑frequency microphones (20 kHz – 200 kHz) with low‑noise preamplifiers.
- Spectrographic analysis software capable of visualizing frequency modulation and temporal patterns.
- Automated detection algorithms that classify call types based on spectral features.
Understanding the acoustic capabilities of rats and mice enhances experimental design, improves welfare assessment, and contributes to comparative studies of mammalian hearing.