How do mice make sounds? - briefly
Mice generate sounds primarily through rapid vibration of their laryngeal vocal folds, producing ultrasonic squeaks that can reach 100 kHz, and by forcing air through the nasal and oral cavities to create clicks and chirps. These vocalizations are coordinated by neural circuits that modulate airflow and muscle tension to encode different social signals.
How do mice make sounds? - in detail
Mice generate acoustic signals through a combination of laryngeal vibration, aerodynamic airflow, and muscular control. The larynx contains paired vocal folds that can be adducted and tensioned by intrinsic laryngeal muscles. When air expelled from the lungs passes through the narrowed glottal opening, the vocal folds oscillate, producing a sound wave. Adjustments in subglottal pressure, fold tension, and aperture size modulate frequency, amplitude, and duration.
Key physiological components:
- Respiratory drive: Diaphragmatic and intercostal muscles create the pressure gradient required for phonation.
- Laryngeal musculature: The cricothyroid, thyroarytenoid, and posterior cricoarytenoid muscles fine‑tune fold tension and position.
- Neural control: Brainstem nuclei (e.g., the nucleus ambiguus) and cortical inputs coordinate timing and pattern of muscle activation.
Mice emit several distinct vocal categories, each associated with specific social contexts:
- Ultrasonic vocalizations (USVs): Frequency range 30–110 kHz, produced during courtship, maternal separation, and territorial encounters. USVs are generated by rapid, high‑frequency oscillations of the vocal folds, often accompanied by precise timing of breath bursts.
- Low‑frequency calls: 3–10 kHz range, observed in aggressive or alarm situations. These calls result from slower fold vibrations and larger glottal apertures.
- Purr‑like sounds: Broadband, low‑amplitude emissions during grooming or contentment, produced by irregular, low‑pressure airflow and partial vocal fold vibration.
Acoustic characteristics are shaped by morphological factors:
- Vocal fold length and mass: Short, thin folds favor high‑frequency output.
- Tracheal dimensions: Narrow trachea increases airflow velocity, supporting ultrasonic production.
- Syrinx absence: Unlike birds, mice lack a dual‑source organ; all sounds originate from the larynx.
Experimental observations using high‑speed videoendoscopy and electromyography reveal that mice can modulate call structure on a millisecond timescale, allowing rapid succession of syllables within a single vocal bout. Pharmacological blockade of laryngeal muscles eliminates both USVs and low‑frequency calls, confirming the essential role of muscular control.
In summary, mouse sound production relies on coordinated respiratory pressure, precise laryngeal muscle action, and specialized vocal fold anatomy, enabling a repertoire of ultrasonic and audible calls that serve communication, mating, and defensive functions.