107
Results from auditory evoked potential (AEP, or “auditory brainstem response”)
studies indicate that the tuning curves of darters, sculpins, and gobies are similar in
profi le (Fig. 3 ). The common pattern is a hearing range effectively below 1 kHz,
with maximum sensitivity below 300 Hz and declining sensitivity with increasing
frequency. In general, the audiograms are consistent with data collected for other
fi shes lacking ancillary auditory specializations (Popper and Fay 1993 ; Ladich and
Fay 2013 ). We report here novel AEP audiograms for Etheostoma neopterum ,
Etheostoma fl abellare , and Etheostoma oophylax (Noel 2012 ; Noel unpublished;
Fig. 3a, b ). Lowest thresholds occurred at 100–200 Hz at 65–80 dB re 1 μm/s
2 ,
which is comparable in both sensitivity and bandwidth to the AEP audiograms collected for another percid, Perca fl uviatilis (Amoser and Ladich 2005 ). In gobies,
pressure audiograms have been collected from Padogobius bonelli and Padogobius
nigricans (Lugli et al. 2003 ), Neogobius melanostomus (Belanger et al. 2010 ; Zeyl
et al. 2013 ), and Pomatoschistus pictus (Bolgan et al. 2012 ; Fig. 3c, d ). The particle
motion audiograms available for Gobius cruentatus (Wysocki et al. 2009 ) and N.
melanostomus found best sensitivities at 100–200 Hz at ~70 dB re 1 μm/s
2 . Cottus
audiogram contours and bandwidths are similar to darters and gobies but thresholds
are lower (Fig. 3e, f ). Best sensitivities occur at 100–200 Hz at ~50 dB re 1 μm/s
2
(~90 dB re 1 μPa), and increase with increasing frequency, although Cottus ricei
exhibits a slight decrease in threshold above 800 Hz.
5 Signaling Effi cacy Within Soundscapes
For acoustic signals to effectively transmit information, sound frequencies must be
detectable by receivers. Many vocalizing fi shes produce low frequency sounds, and
fi shes lacking pressure detection abilities have best hearing sensitivity at frequencies less than 500 Hz (Popper and Fay 1993 , 2011 ; Amorim 2006 ). Darters, sculpins, and gobies follow this pattern. However, within these phylogenetic constraints,
low frequency signals of gobies optimize S/N ratio via (1) a correspondence between
sound dominant frequency and ambient noise acoustic window (Lugli et al. 2003 ;
Lugli 2010 ), and (2) amplifi cation of low frequencies by nest objects, stones, and
bivalve shells (Lugli 2012 , 2013 , 2014 ). In addition to the dominant frequencies in
the freshwater gobies Padogobius bonelli and Padogobius nigricans matching the
ambient acoustic noise window (70–150 Hz), their audiogram best sensitivities at
100 Hz correspond with the lowest spectrum level of ambient noise (Lugli et al.
2003 ). While soundscape analysis is likely an important selective pressure on hearing in both soniferous and non-soniferous fi shes (Schellert and Popper 1992; Popper
and Fay 1993 ; Fay and Popper 2000 ; Ladich 2014 ), the evolution of sound production traits is expected to be constrained by the effi cacy of information transfer in
relation to both soundscapes and receiver hearing characteristics (Endler 1992 ).
Catonotus darters, most Cottus spp., and freshwater gobies often inhabit lotic
stream habitats, where geophysical factors such as water depth, velocity, fl ow
obstructions, and sediment load dictate the soundscape. Stream areas with an unbroConvergent Aspects of Acoustic Communication in Darters, Sculpins, and Gobies
Results from auditory evoked potential (AEP, or “auditory brainstem response”)
studies indicate that the tuning curves of darters, sculpins, and gobies are similar in
profi le (Fig. 3 ). The common pattern is a hearing range effectively below 1 kHz,
with maximum sensitivity below 300 Hz and declining sensitivity with increasing
frequency. In general, the audiograms are consistent with data collected for other
fi shes lacking ancillary auditory specializations (Popper and Fay 1993 ; Ladich and
Fay 2013 ). We report here novel AEP audiograms for Etheostoma neopterum ,
Etheostoma fl abellare , and Etheostoma oophylax (Noel 2012 ; Noel unpublished;
Fig. 3a, b ). Lowest thresholds occurred at 100–200 Hz at 65–80 dB re 1 μm/s
2 ,
which is comparable in both sensitivity and bandwidth to the AEP audiograms collected for another percid, Perca fl uviatilis (Amoser and Ladich 2005 ). In gobies,
pressure audiograms have been collected from Padogobius bonelli and Padogobius
nigricans (Lugli et al. 2003 ), Neogobius melanostomus (Belanger et al. 2010 ; Zeyl
et al. 2013 ), and Pomatoschistus pictus (Bolgan et al. 2012 ; Fig. 3c, d ). The particle
motion audiograms available for Gobius cruentatus (Wysocki et al. 2009 ) and N.
melanostomus found best sensitivities at 100–200 Hz at ~70 dB re 1 μm/s
2 . Cottus
audiogram contours and bandwidths are similar to darters and gobies but thresholds
are lower (Fig. 3e, f ). Best sensitivities occur at 100–200 Hz at ~50 dB re 1 μm/s
2
(~90 dB re 1 μPa), and increase with increasing frequency, although Cottus ricei
exhibits a slight decrease in threshold above 800 Hz.
5 Signaling Effi cacy Within Soundscapes
For acoustic signals to effectively transmit information, sound frequencies must be
detectable by receivers. Many vocalizing fi shes produce low frequency sounds, and
fi shes lacking pressure detection abilities have best hearing sensitivity at frequencies less than 500 Hz (Popper and Fay 1993 , 2011 ; Amorim 2006 ). Darters, sculpins, and gobies follow this pattern. However, within these phylogenetic constraints,
low frequency signals of gobies optimize S/N ratio via (1) a correspondence between
sound dominant frequency and ambient noise acoustic window (Lugli et al. 2003 ;
Lugli 2010 ), and (2) amplifi cation of low frequencies by nest objects, stones, and
bivalve shells (Lugli 2012 , 2013 , 2014 ). In addition to the dominant frequencies in
the freshwater gobies Padogobius bonelli and Padogobius nigricans matching the
ambient acoustic noise window (70–150 Hz), their audiogram best sensitivities at
100 Hz correspond with the lowest spectrum level of ambient noise (Lugli et al.
2003 ). While soundscape analysis is likely an important selective pressure on hearing in both soniferous and non-soniferous fi shes (Schellert and Popper 1992; Popper
and Fay 1993 ; Fay and Popper 2000 ; Ladich 2014 ), the evolution of sound production traits is expected to be constrained by the effi cacy of information transfer in
relation to both soundscapes and receiver hearing characteristics (Endler 1992 ).
Catonotus darters, most Cottus spp., and freshwater gobies often inhabit lotic
stream habitats, where geophysical factors such as water depth, velocity, fl ow
obstructions, and sediment load dictate the soundscape. Stream areas with an unbroConvergent Aspects of Acoustic Communication in Darters, Sculpins, and Gobies