6. SOUND PRODUCTION AND DETECTION
181.
Chagnon (1954) presented strong evidence that Semotilus can orient with
respect to a sound source, especially if there are standing waves present.
Reinhardt (1935) and von Frisch and Dijkgraaf (1935) came to the opposite conclusion, i.e., that fish could not localize a sound. Their data.
however, showed that localization took place at close range to the sound
source. Van Bergeijk (1964) reviewed the available data with respect ta
the nature of the acoustic stimulus presented, and he emphasized that
the distinction between the two forms of acoustic energy must be made:
i.e., between far field (pressure) and near field (displacement). For
localization to take place, a minimum of two receptors is necessary
(Kuroki, 1967). Fishes have, at best, only a single pressure receptor: one
median swim bladder coupled to the two inner ears. Displacement detectors in the form of lateral line organs, however, form a complex array
of numerous units. Van Bergeijk's conclusion is, therefore, that fish are
not able to localize except within the range of the near field of a sound
source (about one-sixth of a wavelength).
Through a combination of neuroanatomical, neurophysiological and
behavioral techniques, Moulton and Dixon ( 1967) demonstrated that
certain directional responses in fish consist of rapid tail flips. These are
two-neuron reflexes involving a sensory and a Mauthner's neuron and are
associated with a rapid escape response, although conditioning can alter
this to an approach response. Moulton and Dixon proposed that these
were directional resonses to a far-field stimulus, but the intensity of the
test sounds was high and the loudspeaker was close to the animal in their
experimental conditions. It is probable that a substantial near field was
generated (cf. comments by Tavolga and van Bergeijk and p. 232 in
Moulton and Dixon, 1967).
Experiments and observations on the movements of carp in a large
tank, monitored by means of a matrix of photoconductive cells, showed
that orientation in a sound field takes place by a sort of klinotaxis. In
response to nodal and antinodal sound pressure variations, the turning
angle of the fish is modified, and it is postulated that this response is
mediated by Mauthner cells ( Kleerekoper and Malar, 1968).
According to the analysis by van Bergeijk ( 1964), elasmobranchs,
lacking a swim bladder, should not be able to detect far-field energy. In
field observations, however, D. R. Nelson and Gruber (1963) and Wisby
and Nelson (1964) were able to attract sharks with low frequency
signals (20-60 Hz). The range over which this attraction took place
(about 200 meters) brings up the possibility that the animals were reacting to a far-field pressure wave. However, sensitivity to displacement
energy in the lemon shark, Negaprion brevirostris, was found to be
below 10 A in some cases (Banner, 1967).
181.
Chagnon (1954) presented strong evidence that Semotilus can orient with
respect to a sound source, especially if there are standing waves present.
Reinhardt (1935) and von Frisch and Dijkgraaf (1935) came to the opposite conclusion, i.e., that fish could not localize a sound. Their data.
however, showed that localization took place at close range to the sound
source. Van Bergeijk (1964) reviewed the available data with respect ta
the nature of the acoustic stimulus presented, and he emphasized that
the distinction between the two forms of acoustic energy must be made:
i.e., between far field (pressure) and near field (displacement). For
localization to take place, a minimum of two receptors is necessary
(Kuroki, 1967). Fishes have, at best, only a single pressure receptor: one
median swim bladder coupled to the two inner ears. Displacement detectors in the form of lateral line organs, however, form a complex array
of numerous units. Van Bergeijk's conclusion is, therefore, that fish are
not able to localize except within the range of the near field of a sound
source (about one-sixth of a wavelength).
Through a combination of neuroanatomical, neurophysiological and
behavioral techniques, Moulton and Dixon ( 1967) demonstrated that
certain directional responses in fish consist of rapid tail flips. These are
two-neuron reflexes involving a sensory and a Mauthner's neuron and are
associated with a rapid escape response, although conditioning can alter
this to an approach response. Moulton and Dixon proposed that these
were directional resonses to a far-field stimulus, but the intensity of the
test sounds was high and the loudspeaker was close to the animal in their
experimental conditions. It is probable that a substantial near field was
generated (cf. comments by Tavolga and van Bergeijk and p. 232 in
Moulton and Dixon, 1967).
Experiments and observations on the movements of carp in a large
tank, monitored by means of a matrix of photoconductive cells, showed
that orientation in a sound field takes place by a sort of klinotaxis. In
response to nodal and antinodal sound pressure variations, the turning
angle of the fish is modified, and it is postulated that this response is
mediated by Mauthner cells ( Kleerekoper and Malar, 1968).
According to the analysis by van Bergeijk ( 1964), elasmobranchs,
lacking a swim bladder, should not be able to detect far-field energy. In
field observations, however, D. R. Nelson and Gruber (1963) and Wisby
and Nelson (1964) were able to attract sharks with low frequency
signals (20-60 Hz). The range over which this attraction took place
(about 200 meters) brings up the possibility that the animals were reacting to a far-field pressure wave. However, sensitivity to displacement
energy in the lemon shark, Negaprion brevirostris, was found to be
below 10 A in some cases (Banner, 1967).