David G. Browning - decibeldb@aol.com
Department of Physics
University of Rhode Island
Kingston, RI 02881
Peter M. Scheifele - scheifel@uconn.edu
Department of Animal Science
University of Connecticut Storrs, CT 06269
Popular version of paper 5aAB7
Presented Friday morning, November 19, 2004
148th ASA Meeting, San Diego, CA
Horses have the largest eyes of any mammal, resulting in exceptional vision
with a nearly 360-degree field of view. As a result, much of a horse's communication
is done visually and vocalization is relatively infrequent compared to poorer
sighted hoofed animals such as pigs.
Perhaps surprisingly then, horses make a rich array of sounds: some non-vocal, such as snorts and blows; to vocal sounds, from gentle sighs to loud roars.
In addition, horses, in contrast to the tonal bellows of cows, goats, and sheep, have the ability to shift frequencies during a vocalization, resulting in the characteristic sound of a whinny.
Frequency analyses indicate that of the approximately seven or eight distinct horse sounds, three - nickers, whinnies, and squeals - are similar in nature. A nicker can be thought of as a quiet whinny and a squeal as a short loud one.
These three have the greatest frequency changes, allowing what might be considered the possibility of expression for an individual horse. The whinny also appears to be the primary means for long range vocal communication.
It has been suggested that the whinny provides a unique acoustic signature to allow horses to identify each other, especially when hidden from view in a herd or under low light conditions.
It is still not known, however, whether the frequency changes can be linked to a specific situation. In other words, are they just an expression of a horse's state of anxiety or do they contain information about the specific situation ?