UCLA

Recent evidence indicates that laboratory mice use elaborate ultrasonic songs, and this behavior possibly may be learned. In the present study, air pressure was manipulated while producing sound in isolated larynges from wild type male laboratory mice post mortem. The present study indicates that, consistent with findings in other mammals, changes in subglottal pressure induce linear changes in the fundamental frequency of periodic sound, sudden non-linear frequency jumps, biphonation, and sudden changes from periodic to aperiodic sound depending on the absolute value of air pressure applied. The linear and non-linear changes in phonations by the isolated mouse larynx cover virtually all aspects of natural vocalizations produced by adult male mice. Data from simulated contractions of the main laryngeal muscle for frequency control, the cricothyroid, suggest that adduction of the thyroid plays only a minor (if any) role for frequency control in the mouse larynx, especially when compared with the larynx of bats. Therefore, most spectral aspects of mouse vocalizations appear to be based upon changing the tracheal air flow rather than contracting the cricothyroid muscle.