a number of times (Fish and Mowbray 1970; Myrberg 1981; Bass and Baker
1991; Ladich and Bass 1998). The majority of well-documented teleost
sounds are brief (50–200 msec), pulse-like signals that are broadband, with
fundamental frequencies typically less than 400 Hz (Winn 1964; Fish and
Mowbray 1970; Fine et al. 1977; Myrberg 1981; Ladich 1997). These sounds
have been documented in aggressive and/or reproductive contexts. Longduration signals on the order of seconds to minutes have been more specifically associated with courtship. This includes the boatwhistles of toadfish
(Fine et al. 1977), the hums of midshipman (Bass et al. 1999), and the moans
of mormyrids (Crawford et al. 1997). Sound intensities near the source are
typically in the 120–130 dB re 1 mPa range (e.g., see Crawford et al. 1997;
Barimo and Fine 1998; Bass et al. 1999). Most sonic species of teleost fishes
are found in shallow water habitats either seasonally or on a perennial basis.
As with the vocalizations of cetaceans and other vertebrates, those of
teleost fishes may vary in a number of parameters, including repetition rate,
duration, amplitude, and frequency (see references above). To illustrate the
nature of some of this variation, we present examples of the vocal signals
from one species, the plainfin midshipman fish (Porichthys notatus), that has
been extensively studied. P. notatus is reproductively active at night in water
depths up to 5 m at high tide in some locales (Bass and Marchaterre unpublished). Midshipman have two male phenotypes or morphs, type I and type
II (Bass 1996). Type I males build nests in the intertidal zone, from which
they acoustically court females (Fig. 2.9). Type II males neither build nests
nor court females.The vocal repertoire of type II males, like females, is fairly
limited; they produce isolated, low-amplitude grunt-like signals (Brantley
and Bass 1994). Type I males have the far more dynamic repertoire; they
produce long-duration (sometimes > 1 h) “hums” during courtship (top
panel, Fig. 2.10). Hums are multiharmonic signals with a fundamental
frequency near 100 Hz and several prominent harmonics. Brief-duration
“grunts” are produced either individually or in trains of more than 100
during agonistic encounters (bottom panel, Fig. 2.10); their fundamental
frequency is also close to 100 Hz. “Growls” are intermediate in duration
between single grunts and hums and show frequency modulation with significant energy well below 100 Hz (center panel, Fig. 2.10). Most teleosts
generate nonoverlapping sounds (e.g., see Fine et al. 1977). However,
an interesting example of the interaction of two conspecific signals is the
overlapping hums of neighboring males, which establish acoustic beats
with a modulation frequency equal to the difference frequency between the
fundamental frequencies of each individual’s call (Fig. 2.11).
12.2. Shallow Water Sound Communication
A variety of studies have used pressure-sensitive hydrophones to study
transmission loss of naturally occurring vocalizations in shallow water habitats. Fine and Lenhardt (1983) studied transmission loss for pure tones and
46
A.H. Bass and C.W. Clark
1991; Ladich and Bass 1998). The majority of well-documented teleost
sounds are brief (50–200 msec), pulse-like signals that are broadband, with
fundamental frequencies typically less than 400 Hz (Winn 1964; Fish and
Mowbray 1970; Fine et al. 1977; Myrberg 1981; Ladich 1997). These sounds
have been documented in aggressive and/or reproductive contexts. Longduration signals on the order of seconds to minutes have been more specifically associated with courtship. This includes the boatwhistles of toadfish
(Fine et al. 1977), the hums of midshipman (Bass et al. 1999), and the moans
of mormyrids (Crawford et al. 1997). Sound intensities near the source are
typically in the 120–130 dB re 1 mPa range (e.g., see Crawford et al. 1997;
Barimo and Fine 1998; Bass et al. 1999). Most sonic species of teleost fishes
are found in shallow water habitats either seasonally or on a perennial basis.
As with the vocalizations of cetaceans and other vertebrates, those of
teleost fishes may vary in a number of parameters, including repetition rate,
duration, amplitude, and frequency (see references above). To illustrate the
nature of some of this variation, we present examples of the vocal signals
from one species, the plainfin midshipman fish (Porichthys notatus), that has
been extensively studied. P. notatus is reproductively active at night in water
depths up to 5 m at high tide in some locales (Bass and Marchaterre unpublished). Midshipman have two male phenotypes or morphs, type I and type
II (Bass 1996). Type I males build nests in the intertidal zone, from which
they acoustically court females (Fig. 2.9). Type II males neither build nests
nor court females.The vocal repertoire of type II males, like females, is fairly
limited; they produce isolated, low-amplitude grunt-like signals (Brantley
and Bass 1994). Type I males have the far more dynamic repertoire; they
produce long-duration (sometimes > 1 h) “hums” during courtship (top
panel, Fig. 2.10). Hums are multiharmonic signals with a fundamental
frequency near 100 Hz and several prominent harmonics. Brief-duration
“grunts” are produced either individually or in trains of more than 100
during agonistic encounters (bottom panel, Fig. 2.10); their fundamental
frequency is also close to 100 Hz. “Growls” are intermediate in duration
between single grunts and hums and show frequency modulation with significant energy well below 100 Hz (center panel, Fig. 2.10). Most teleosts
generate nonoverlapping sounds (e.g., see Fine et al. 1977). However,
an interesting example of the interaction of two conspecific signals is the
overlapping hums of neighboring males, which establish acoustic beats
with a modulation frequency equal to the difference frequency between the
fundamental frequencies of each individual’s call (Fig. 2.11).
12.2. Shallow Water Sound Communication
A variety of studies have used pressure-sensitive hydrophones to study
transmission loss of naturally occurring vocalizations in shallow water habitats. Fine and Lenhardt (1983) studied transmission loss for pure tones and
46
A.H. Bass and C.W. Clark