Hearing Specialists & Non-Specialists
Investigators working with fish bioacoustics used to refer to fishes that have a narrow hearing bandwidth and poor sensitivity as “hearing generalists” (or “non-specialists”), while fishes that could detect a wider hearing bandwidth and had greater sensitivity were referred to as specialists. However, as more was learned about fish hearing mechanism and capacities, these terms became hard to apply, since it was clear there were gradations in hearing capabilities. Popper and Fay, in a paper in Hearing Research in 2011, proposed that these terms be dropped because of the gradation. While this was widely accepted by investigators, it is now apparent that the lack of relatively concise terminology for fish hearing capabilities makes it hard to discuss fish hearing.
In a new paper, Popper, Hawkins, and Sisneros (2011) resurrect the terms specialist and non-specialist but use them with modifiers to express the specific structure of function that is considered a specialization. Moreover, this resurrection recognizes that hearing specializations in fishes may not only be related to increased bandwidth and/or sensitivity, but to other, perhaps more important, aspects of hearing such as sound source localization, discrimination between sounds, and detection of sounds in the presence of masking signals.
This figure below shows our views of the continuum of hearing for fishes first proposed by Popper and Fay (2011), starting with fishes with no gas bubble, such as elasmobranchs and flatfish, that do not detect sound pressure, to fishes, including the otophysans, that are very well adapted for detection of sound pressure. Width of the arrows depict relative involvement of particle motion (blue) and sound pressure (red) in hearing in different species. Figure derived from Popper and Fay (2011) as modified by Putland et al. (2019). (Figure © 2021 Anthony D. Hawkins, all rights reserved.)