156
WILLIAM N. TAVOLGA
given in papers by Fish et al. (1952) and Fish (1954). The tables are
based primarily on recordings made under laboratory conditions, and,
in many cases, the stimulus for sound production was some noxious
stimulus such as electric shock, These data, therefore, must be treated
cautiously and specific conclusions as to sonic characteristics of a given
species need to be corroborated with field recordings under natural conditions. Much of the following discussion is based upon reviews by Fish
( 1954, 1964), N. B. Marshall (1962), Moulton (1958, 1963), Schneider
( 1967), Tavolga (1960, 196413, 1965), and Winn (1964).
1. STRIDULATORY SOUNDS
Sounds produced by the grating of pharyngeal denticles, jaw teeth, fin
rays, or bones are essentially nonharmonic in structure, i.e., they do not
resolve, in a spectrogram, into a series of horizontal parallel bars at
harmonic intervals. Such sounds contain many harmonically unrelated
frequencies (Fig. 11).
Two general categories of stridulatory sounds can be distinguished on
the basis of predominant pitch. High frequency stridulations are usually
produced by the gnashing of jaw teeth and, sometimes, the patches of
pharyngeal denticles during feeding. The component frequencies extend
continuously from below 100 to over 8000 Hz. Predominant frequencies
are in the 1000-4000-Hz range, and durations are extremely variable.
6
2 4
2
I
012 t 0.4 0.6
sec
Fig. 11. Spectrogram of stridulatory sounds produced by a jack, Carunx. A
frequency-intensity section shown on the right was taken at the point indicated by
the arrow. This is characteristic of short, broad-band pulsed sounds. After Tavolga
(1965), with permission of the U. S. Naval Training Device Center.
WILLIAM N. TAVOLGA
given in papers by Fish et al. (1952) and Fish (1954). The tables are
based primarily on recordings made under laboratory conditions, and,
in many cases, the stimulus for sound production was some noxious
stimulus such as electric shock, These data, therefore, must be treated
cautiously and specific conclusions as to sonic characteristics of a given
species need to be corroborated with field recordings under natural conditions. Much of the following discussion is based upon reviews by Fish
( 1954, 1964), N. B. Marshall (1962), Moulton (1958, 1963), Schneider
( 1967), Tavolga (1960, 196413, 1965), and Winn (1964).
1. STRIDULATORY SOUNDS
Sounds produced by the grating of pharyngeal denticles, jaw teeth, fin
rays, or bones are essentially nonharmonic in structure, i.e., they do not
resolve, in a spectrogram, into a series of horizontal parallel bars at
harmonic intervals. Such sounds contain many harmonically unrelated
frequencies (Fig. 11).
Two general categories of stridulatory sounds can be distinguished on
the basis of predominant pitch. High frequency stridulations are usually
produced by the gnashing of jaw teeth and, sometimes, the patches of
pharyngeal denticles during feeding. The component frequencies extend
continuously from below 100 to over 8000 Hz. Predominant frequencies
are in the 1000-4000-Hz range, and durations are extremely variable.
6
2 4
2
I
012 t 0.4 0.6
sec
Fig. 11. Spectrogram of stridulatory sounds produced by a jack, Carunx. A
frequency-intensity section shown on the right was taken at the point indicated by
the arrow. This is characteristic of short, broad-band pulsed sounds. After Tavolga
(1965), with permission of the U. S. Naval Training Device Center.