410
clinical trials. As genetic manipulations can produce disorganized placement of new
hair cells in the mammalian organ of Corti without recovery of hearing (Löwenheim
et al. 1999 ; Mansour et al. 2009 ), it is likely that functional hair cell regeneration in
the cochlea will involve more than a single gene or cellular pathway. However, the
utility of the zebrafi sh as an auditory model may make them very valuable in further
characterizing the many genes and pathways involved in hair cell death and regeneration in humans. The usage of zebrafi sh screens to fi nd effective pharmaceutical
compounds with reduced ototoxicity should also continue to be an area of productive research effort.
Research on the effects of anthropogenic sounds on fi shes is relatively new compared to biomedical studies of hair cells. Audiograms have only been recorded for
a limited number of taxa out of the over 27,000 species of fi shes, and sound-induced
hearing loss has been tested in less than 20 species. Thus, data on how anthropogenic sound effects fi shes is needed on more species. Models to predict soundinduced hearing loss have been developed using the SPL of the acoustic stimulus
and the hearing sensitivity of the species (Smith et al. 2004b ; Smith 2012 ), but
future models should use particle motion sensitivity measures and account for
species- specifi c pressure versus particle motion sensitivity. There are also a number
of questions that are still unanswered: Can fi sh exhibit permanent hearing loss if the
sensory epithelia is damaged suffi ciently? What is the best measure of a sound
stimulus to predict hearing loss in fi shes, e.g., peak sound pressure, SEL, particle
velocity, or intensity (i.e., acoustic energy fl ux)? What are the behavioral and survival effects for fi shes affected by anthropogenic sound? As more researchers are
investigating how anthropogenic sound affects animals, we believe that progress
will be made within the next decade to answer these and other questions related to
acoustic exposure of fi shes.
Acknowledgements The authors express their gratitude to both Arthur N. Popper and Richard
R. Fay for their many years of exceptional research on fi sh hearing and bioacoustics and their
leadership and mentoring in this fi eld. MES thanks Art Popper for his fi rst postdoctoral job and
for the wise advice, friendship, and consummate mentoring at the University of Maryland, where
the author began his career in fi sh hearing research and started examining the effects of sound on
fi shes. Art provided numerous career development opportunities to present research at conferences, to receive specifi c training, e.g., a course on Acoustic Communication in Denmark, to
team- teach courses, to collaborate on broader lab projects, and to network with other researchers
in the fi eld of fi sh hearing. Of course, Dick Fay was one of those colleagues that Art introduced
MES to and he is grateful for Dick’s advice on projects, particularly the work on the tonotopic
organization of the goldfi sh saccule. MES thanks numerous undergraduate researchers, former
graduate students Julie Schuck, Chia-Hui Lin, Yajie Wang, Gopinath Rajadinakaran, and Bethany
Coffey, and former postdoctoral researchers Todd Penberthy and Huifang Sun, for their many
hours of auditory evoked potential recordings and inner ear dissections to examine hair cell and
hearing loss in fi shes.
Research in the Smith lab was supported by the National Institute of General Medical Sciences
of the NIH (P20 RR-16481, 8 P20 GM103436-12, 2 P20 GM103436-14), a Kentucky Science and
Engineering Foundation Research & Development Excellence Grant (KSEF-148-502-14-325),
and an NSF SOMAS Award (DUE-0426266). We thank Drs. Allison Coffi n and Joseph Sisneros
for helpful comments on an earlier draft of this manuscript.
M.E. Smith and J.D. Monroe
clinical trials. As genetic manipulations can produce disorganized placement of new
hair cells in the mammalian organ of Corti without recovery of hearing (Löwenheim
et al. 1999 ; Mansour et al. 2009 ), it is likely that functional hair cell regeneration in
the cochlea will involve more than a single gene or cellular pathway. However, the
utility of the zebrafi sh as an auditory model may make them very valuable in further
characterizing the many genes and pathways involved in hair cell death and regeneration in humans. The usage of zebrafi sh screens to fi nd effective pharmaceutical
compounds with reduced ototoxicity should also continue to be an area of productive research effort.
Research on the effects of anthropogenic sounds on fi shes is relatively new compared to biomedical studies of hair cells. Audiograms have only been recorded for
a limited number of taxa out of the over 27,000 species of fi shes, and sound-induced
hearing loss has been tested in less than 20 species. Thus, data on how anthropogenic sound effects fi shes is needed on more species. Models to predict soundinduced hearing loss have been developed using the SPL of the acoustic stimulus
and the hearing sensitivity of the species (Smith et al. 2004b ; Smith 2012 ), but
future models should use particle motion sensitivity measures and account for
species- specifi c pressure versus particle motion sensitivity. There are also a number
of questions that are still unanswered: Can fi sh exhibit permanent hearing loss if the
sensory epithelia is damaged suffi ciently? What is the best measure of a sound
stimulus to predict hearing loss in fi shes, e.g., peak sound pressure, SEL, particle
velocity, or intensity (i.e., acoustic energy fl ux)? What are the behavioral and survival effects for fi shes affected by anthropogenic sound? As more researchers are
investigating how anthropogenic sound affects animals, we believe that progress
will be made within the next decade to answer these and other questions related to
acoustic exposure of fi shes.
Acknowledgements The authors express their gratitude to both Arthur N. Popper and Richard
R. Fay for their many years of exceptional research on fi sh hearing and bioacoustics and their
leadership and mentoring in this fi eld. MES thanks Art Popper for his fi rst postdoctoral job and
for the wise advice, friendship, and consummate mentoring at the University of Maryland, where
the author began his career in fi sh hearing research and started examining the effects of sound on
fi shes. Art provided numerous career development opportunities to present research at conferences, to receive specifi c training, e.g., a course on Acoustic Communication in Denmark, to
team- teach courses, to collaborate on broader lab projects, and to network with other researchers
in the fi eld of fi sh hearing. Of course, Dick Fay was one of those colleagues that Art introduced
MES to and he is grateful for Dick’s advice on projects, particularly the work on the tonotopic
organization of the goldfi sh saccule. MES thanks numerous undergraduate researchers, former
graduate students Julie Schuck, Chia-Hui Lin, Yajie Wang, Gopinath Rajadinakaran, and Bethany
Coffey, and former postdoctoral researchers Todd Penberthy and Huifang Sun, for their many
hours of auditory evoked potential recordings and inner ear dissections to examine hair cell and
hearing loss in fi shes.
Research in the Smith lab was supported by the National Institute of General Medical Sciences
of the NIH (P20 RR-16481, 8 P20 GM103436-12, 2 P20 GM103436-14), a Kentucky Science and
Engineering Foundation Research & Development Excellence Grant (KSEF-148-502-14-325),
and an NSF SOMAS Award (DUE-0426266). We thank Drs. Allison Coffi n and Joseph Sisneros
for helpful comments on an earlier draft of this manuscript.
M.E. Smith and J.D. Monroe