In:
Journal of Experimental Biology, The Company of Biologists, Vol. 218, No. 6 ( 2015-03-15), p. 907-914
Abstract:
Orangutans produce alarm calls called kiss-squeaks, which they sometimes modify by putting a hand in front of their mouth. Through theoretical models and observational evidence, we show that using the hand when making a kiss-squeak alters the acoustics of the production in such a way that more formants per kilohertz are produced. Our theoretical models suggest that cylindrical wave propagation is created with the use of the hand and face as they act as a cylindrical extension of the lips. The use of cylindrical wave propagation in animal calls appears to be extremely rare, but is an effective way to lengthen the acoustic system; it causes the number of resonances per kilohertz to increase. This increase is associated with larger animals, and thus using the hand in kiss-squeak production may be effective in exaggerating the size of the producer. Using the hand appears to be a culturally learned behavior, and therefore orangutans may be able to associate the acoustic effect of using the hand with potentially more effective deterrence of predators.
Type of Medium:
Online Resource
ISSN:
1477-9145
,
0022-0949
Language:
English
Publisher:
The Company of Biologists
Publication Date:
2015
detail.hit.zdb_id:
1482461-9
SSG:
12
