1. ANATOMY AND PHYSIOLOGY OF THE CENTRAL NERVOUS SYSTEM
67
volved. Perhaps different types of units are involved which cover different
frequency ranges. Both units, however, respond to low frequencies, but
only units with certain special spontaneous activity respond to high frequencies. These two types of units could provide information on the
frequency of sound.
Saccular microphonics have been recorded from curarized midshipman, Porichthys notatus (Cohen and Winn, 1967). Following cautery
of the sacculus the microphonic potential virtually disappears. The microphonic appears to arise from the hair cells on the macula of the sacculus
as in other vertebrates. The hearing frequency curve for the midshipman
based on a 20-pV microphonic response indicated that the ear can
detect a frequency range of 30-210 Hz. The low threshold of the ear at
150 Hz corresponded to the fundamental frequency of the sounds produced by these fish. Cohen and Winn (1967) make the point that most
of the higher frequencies of fish sound recorded on sonograms apparently (as seen by their data) cannot be utilized as information by the
fish ear and are most probably artifacts of the sound-transmitting structures within the fish body.
Saccular microphonics have been utilized in codfish, Gadus morhua,
and sculpin, Cottus scorpius, to determine the animals’ ability to perceive
sound in the far field, up to 10 meters from the source (Enger and
Andersen, 19f37). Other studies have been on near field acoustic reception in laboratory studies. Codfish ( ostariophysids ) displayed a microphonic amplitude potential which was a function of sound pressure only
for distances from 0.7 to 10 meters, from an underwater loudspeaker,
and for frequencies up to 200 Hz. Microphonic responses were also
recorded for frequencies up to 800-1000 Hz. In the sculpin (nonostariophysid ) the microphonic potential was dependent upon both the
sound pressure and distance. However, no microphonic was recorded
after the animal was 1 meter or more from the sound source. It appears
that a swim bladder is essential for fish to hear propagated sound waves.
The swim bladder generated near-field effects by local water displacements. This local near-field effect in turn is capable of stimulating
auditory receptors ( Enger and Andersen, 1967).
In a theoretical paper dealing with directional and nondirectional
hearing in fish, van Bergeijk (1964) argues that since most fish have only
one pressure receptor for far-field acoustic discrimination, they cannot
localize the source of sound in the far field. However, near-field acoustic
localization requires two displacement receptors which are present in
ample numbers in the lateral line. From the data of Enger and Andersen
(1967) it would appear that far-field acoustic perception is dependent
upon the presence of a swim bladder which results in the production of
67
volved. Perhaps different types of units are involved which cover different
frequency ranges. Both units, however, respond to low frequencies, but
only units with certain special spontaneous activity respond to high frequencies. These two types of units could provide information on the
frequency of sound.
Saccular microphonics have been recorded from curarized midshipman, Porichthys notatus (Cohen and Winn, 1967). Following cautery
of the sacculus the microphonic potential virtually disappears. The microphonic appears to arise from the hair cells on the macula of the sacculus
as in other vertebrates. The hearing frequency curve for the midshipman
based on a 20-pV microphonic response indicated that the ear can
detect a frequency range of 30-210 Hz. The low threshold of the ear at
150 Hz corresponded to the fundamental frequency of the sounds produced by these fish. Cohen and Winn (1967) make the point that most
of the higher frequencies of fish sound recorded on sonograms apparently (as seen by their data) cannot be utilized as information by the
fish ear and are most probably artifacts of the sound-transmitting structures within the fish body.
Saccular microphonics have been utilized in codfish, Gadus morhua,
and sculpin, Cottus scorpius, to determine the animals’ ability to perceive
sound in the far field, up to 10 meters from the source (Enger and
Andersen, 19f37). Other studies have been on near field acoustic reception in laboratory studies. Codfish ( ostariophysids ) displayed a microphonic amplitude potential which was a function of sound pressure only
for distances from 0.7 to 10 meters, from an underwater loudspeaker,
and for frequencies up to 200 Hz. Microphonic responses were also
recorded for frequencies up to 800-1000 Hz. In the sculpin (nonostariophysid ) the microphonic potential was dependent upon both the
sound pressure and distance. However, no microphonic was recorded
after the animal was 1 meter or more from the sound source. It appears
that a swim bladder is essential for fish to hear propagated sound waves.
The swim bladder generated near-field effects by local water displacements. This local near-field effect in turn is capable of stimulating
auditory receptors ( Enger and Andersen, 1967).
In a theoretical paper dealing with directional and nondirectional
hearing in fish, van Bergeijk (1964) argues that since most fish have only
one pressure receptor for far-field acoustic discrimination, they cannot
localize the source of sound in the far field. However, near-field acoustic
localization requires two displacement receptors which are present in
ample numbers in the lateral line. From the data of Enger and Andersen
(1967) it would appear that far-field acoustic perception is dependent
upon the presence of a swim bladder which results in the production of