8
Psychoacoustic Studies of Dolphin
and Whale Hearing
PAUL E. NACHTIGALL, DAVID W. LEMONDS, AND
HERBERT L. ROITBLAT
1. Introduction
Whales and dolphins have evolved in a sensory world very unlike our own.
Although one can guess what the perceptions of a cetacean might be, it is
impossible to "get inside a dolphins head" and experience what it must be
like to hear sounds over 100 kHz and discern fine details of the environment, conspecifics, and prey via echolocation. It is possible, however, using
psychophysical techniques first developed for human measurements, to
characterize some properties of cetacean perception and accurately
measure the acoustic sensations that are experienced by whales and
dolphins.
Psychophysics began as an attempt to develop a "theory of the relation
of body and mind.... As an exact science psychophysics, like physics, must
rest on experience and the mathematical connection of those empirical facts
that demand a measure of what is experienced or, when such a measure is
not available, of a search for it. Since the measure of physical magnitude
is already known, the first and main task of this work will be to establish
the as yet nonexistent measure of psychic magnitudes; the second will be
to take up the applications and detailed arguments that develop from it"
(Fechner 1860, Preface). The techniques Fechner formulated became the
foundation for modern psychophysical investigations, and for experimental
psychology in general.
The functional relationship between physical quantities and psychological quantities can be generally expressed as:
'I'=/(<\»
where 'I' represents the sensation (psychological event) measured in terms
of observable behavior, and <\> represents physical properties of the stimuli.
Psychoacoustics is a subset of psychophysics, with the focus on acoustic or
auditory stimuli (Yost 1993). The relationship between the perceived quantities and the physical quantities on which they depend is typically regular,
but is rarely a simple one-for-one correspondence. That is, the psychophys330
Psychoacoustic Studies of Dolphin
and Whale Hearing
PAUL E. NACHTIGALL, DAVID W. LEMONDS, AND
HERBERT L. ROITBLAT
1. Introduction
Whales and dolphins have evolved in a sensory world very unlike our own.
Although one can guess what the perceptions of a cetacean might be, it is
impossible to "get inside a dolphins head" and experience what it must be
like to hear sounds over 100 kHz and discern fine details of the environment, conspecifics, and prey via echolocation. It is possible, however, using
psychophysical techniques first developed for human measurements, to
characterize some properties of cetacean perception and accurately
measure the acoustic sensations that are experienced by whales and
dolphins.
Psychophysics began as an attempt to develop a "theory of the relation
of body and mind.... As an exact science psychophysics, like physics, must
rest on experience and the mathematical connection of those empirical facts
that demand a measure of what is experienced or, when such a measure is
not available, of a search for it. Since the measure of physical magnitude
is already known, the first and main task of this work will be to establish
the as yet nonexistent measure of psychic magnitudes; the second will be
to take up the applications and detailed arguments that develop from it"
(Fechner 1860, Preface). The techniques Fechner formulated became the
foundation for modern psychophysical investigations, and for experimental
psychology in general.
The functional relationship between physical quantities and psychological quantities can be generally expressed as:
'I'=/(<\»
where 'I' represents the sensation (psychological event) measured in terms
of observable behavior, and <\> represents physical properties of the stimuli.
Psychoacoustics is a subset of psychophysics, with the focus on acoustic or
auditory stimuli (Yost 1993). The relationship between the perceived quantities and the physical quantities on which they depend is typically regular,
but is rarely a simple one-for-one correspondence. That is, the psychophys330