Evidence for the laryngeal source of ultrasonic and audible cries of rodents

The audible cries of three species of young myomorph rodents were found to be emitted through the nose and the mouth, buccal and nasal cavity resonances being involved in the production of the formant structures of the emitted cries. Ultrasonic cries were found to be emitted mainly through the mouth, with no evidence for the involvement of cavity resonances. Nerve sectioning experiments on adult and young rats implicated the larynx as the source of both their audible and their ultrasonic cries. However, consideration of the considerable differences in physical structure between the typically "vocal" audible cries and the ultrasonic cries, as well as other differences noted in the experimental conditions here and elsewhere, leads to the conclusion that the rodent larynx may operate in two quite different sound production modes.