Presentations: We presented the baby rhino study at the 2003 spring national Acoustical Society of America conference and the horse study at the Regional ASA (it was not done in time to submit to the national)













4aAB9. Songlike vocalizations from a Sumatran rhinoceros calf (Dicerorhinus sumatrensis).
Author: Elizabeth von Muggenthaler
Location: Fauna Commun.s Res. Inst.,
Author: Paul Reinhart
Location: Cincinnati Zoo, Cincinnati, OH


Within the last ten years the Sumatran rhino population has dropped 50%, and only 200--300 individuals exist, with five in captivity. Their native habitat is dense tropical forest and they are solitary, therefore much of their behavior remains unknown. Sumatrans are the smallest living rhino, standing 0.9--1.5 m tall, and are covered in coarse, reddish-brown hair. The first Sumatran rhinoceros born in captivity in 112 years, and the first calf ever recorded, is 17 months old and weighs 448 kg. At the Cincinnati Zoo this male calf was recorded from 1--3 m, using two Statham radio microphones, and one TCD-D8 Sony DAT recorder (9 Hz--22 kHz). Analysis, including power spectrums, spectrographic functions, and cross correlations were performed using National Instrument's Polynesia. Preliminary analysis indicates that the calf's vocalizations are similar in structure to adult Sumatran vocalizations, although there are some distinctions. ``Eeps'' and ``whales'' that are found in adult repertoires are produced by the calf. However, signals from the calf are higher in frequency, and the calf does not vocalize as consistently as the adults. The calf has yet to produce a ``whistle blow,'' which is an adult vocalization that has a strong infrasonic component.

Click on the button to hear baby Andalas!






















Excerpts from "Infrasound from Equus Caballus" presented at the Spring conference of the Acoustical Society of America North Carolina Regional Chapter. Authors: E. von Muggenthaler, Philip Hale, Ralph R. Conti

For centuries, the domestic horse (Equus Caballus) has been an integral part of human life. Although some research on the behavior of the wild and domesticated horse exists, there has been limited understanding of the role of communication in their social structure. The authors are not aware of any prior horse vocalization research.

Common horse vocalizations include squeals of aggression and whinnies for facilitating social contact over distance. In donkeys (Equus asinus) there are mouth movements called jawing, yawing, or clapping. This is the opening or closing of the mouth which make a characteristic sound that is audible to humans, (Mcdonnell, 1998). Horses have a unique physiological structure called the auditory tube diverticulum or guttural pouch whose true purpose, remains unknown. The guttural pouches are a pair of pouches located dorso-posteriously to the posterior pharynx. These structures are only found in Equid family and they are dilations of the Eustachian tubes, thin membranous channels that connect the nasopharynx with each middle ear. The capacity of the guttural pouch in adult horses is 472 cm3, and 145 cm2 in foals (Manglai et al., 2000). Guttural pouches perform a role of air exchange between the auditory tube diverticulum, and middle ear (Baptiste, 1997). In 1911 it was proposed that the guttural pouches serve to aid in normal swallowing, equalizing of pressure on either side of the tympanic membrane. Several recent theories about the guttural pouch have indicated that it may be used to cool the blood circulating in the brain during heavy exercise, (Baptiste, 1998), however it is generally accepted that air enters and leaves the pouches during expiration, so the function of the guttural pouches remains open to debate (Hodgson, 1998).

In February 2003, Ocala Florida and North Carolina 11 horses were recorded.

In Ocala two horse stalls were treated with sound suppression panels, by AVL Systems.


Horses produce infrasound.

Soundproofing for bio-acoustics research is suggested when possible.

Order Perrisodactlya including Equidae and Rhinocerotidae produce infrasound. In Order Artiodactyla includes Hippopotamidae and Giraffidae whom produce infrasound.

It is suggested that the guttural pouches are responsible for the generation of low frequency sound, and also may play a role in the reception of infrasound.

The use of infrasound may be why horses are known to "spook" when human observers detect nothing.

Horse stables should be better soundproofed

Horses are herd animals and may rely on infrasound to keep the herd together, or communicate over distance like elephants.







Ed Walsh and his collegues have verified our prior tiger research, and are taking an interesting and comprehensive look at the tiger's vocal repertoire.

4aAB3. Acoustic communication in Panthera tigris: A study of tiger vocalization and auditory receptivity.

Author: Edward J. Walsh
Location: Boys Town Natl. Res. Hospital, 555 N. 30th St., Omaha, NE 68131
Author: Lily M. Wang
Location: Univ. of Nebraska, Omaha, NE 68182
Author: Douglas L. Armstrong
Location: Henry Doorly Zoo, Omaha, NE 68108
Author: Thomas Curro
Location: Henry Doorly Zoo, Omaha, NE 68108
Author: Lee G. Simmons
Location: Henry Doorly Zoo, Omaha, NE 68108
Author: JoAnn McGee
Location: Boys Town Natl. Res. Hospital, Omaha, NE 68131


Acoustic communication represents a primary mode of interaction within the sub-species of Panthera tigris and it is commonly known that their vocal repertoire consists of a relatively wide range of utterances that include roars, growls, grunts, hisses and chuffling, vocalizations that are in some cases produced with extraordinary power. P. tigris vocalizations are known to contain significant amounts of acoustic energy over a wide spectral range, with peak output occurring in a low frequency bandwidth in the case of roars. von Muggenthaler (2000) has also shown that roars and other vocal productions uttered by P. tigris contain energy in the infrasonic range. While it is reasonable to assume that low and infrasonic acoustic cues are used as communication signals among conspecifics in the wild, it is clearly necessary to demonstrate that members of the P. tigris sub-species are responsive to low and infrasonic acoustic signals. The auditory brainstem response has proven to be an effective tool in the characterization of auditory performance among tigers and the results of an ongoing study of both the acoustical properties of P. tigris vocalizations and their auditory receptivity support the supposition that tigers are not only responsive to low frequency stimulation, but exquisitely so.