Charles H. Brown
Fritz E. Brown
K. Leigh Santos
Paul A. Dagenais
Depts. of Psychol. and Speech Pathol. and Audiol., Univ. South Alabama, Mobile, AL 36688
Simultaneous acoustic and laryngographic recordings were made of 176 blue monkey (Cercopithecus mitis) vocalizations. Four classes of periodic vocalizations were identified. In class I calls the rate of phonation ranged from 547 to 1211 Hz. The acoustic output of class I calls was harmonically related to the rate of phonation and ranged from approximately 1 to 9 kHz. Class II signals exhibited a reduced amplitude in the Lx signal consistent with the loft register of phonation. The rate of phonation of class II calls ranged from 1289 to 2177 Hz. The acoustic spectrum of these tonal signals was composed of harmonically related bands. The frequency of the lowest band equaled the frequency of phonation. Class III calls exhibited attributes in the Lx wave that were consistent with the idea of different surfaces of the vocal folds vibrating at different rates. In some calls the putative low-frequency source oscillated at about 850 Hz, and the putative high-frequency source oscillated at about 4200 Hz. The fourth class of signals resembled class I calls except that the signal was emitted as a series of pulses or trills. [Work supported by NIDCD.]