| Autor: |
SUTHERS, RODERICK A., FATTU, JAMES M. |
| Zdroj: |
American Zoologist; Oct1973, Vol. 13 Issue 4, p1215-1226, 12p |
| Abstrakt: |
The echolocative pulses emitted at high repetition rates by bats pose a number of questions regarding the mechanism of their production. We have investigated some physiologic parameters of vocalization in the North American Vespertilionid bat , including pulse insertion within the respiratory cycle and subglottic pressure changes accompanying these intense sounds. Subglottic pressures are considerably higher than those characteristic of human speech and, therefore, require a substantial structure to act as a glottal stop. We suggest that this is the role of the vocal fold and that the thin, paired vocal and ventricular membranes are the ultrasonic generators. The cricothyroid muscle, which is thought to influence sound frequency by altering the tension on these membranes, contracts just prior to each ultrasonic vocalization and relaxes during phonation. Cricothyroid muscle relaxation may gradually decrease the tension on the membranes and create the downward frequency sweep characteristic of most pulses. [ABSTRACT FROM PUBLISHER] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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