It's based on a number
of acoustic cues and heat - related transfer functions, which essentially reverse engineer the way human hearing works to recreate sounds in what seems like a 3D space.
In general, increasingly threatening stimuli elicited alarm calls with increases in F0 and in formant locations, and increasing numbers of
these acoustic cues in vocal stimuli elicited increased vigilance and flight behavior in listening elephants.
The variation in
acoustic cues can be seen in examples taken from three species of Cercopithecus, in which vervet monkeys, C. aethiops, separate alarm calls by the location of dominant frequencies [2], Campbell's monkeys, C. campbelli, separate them by call duration, and by the location and dynamic changes in dominant frequencies [4], while Diana monkeys, C. diana, separate them by call duration, fundamental frequency, and formant frequency characteristics [5]--[7].
We played one natural and two experimentally modified sequences of calls, in order to explore
the acoustic cues responsible for behavioral responses in listeners.
These giants of the sea utilize ocean currents, temperature changes,
acoustic cues and the earth's magnetic field to find their way here to the world's most remote island chain.