The Role of Gas-Holding Structures in Fish Hearing: An Acoustically Evolved Potentials Approach

Fish varies greatly in their sensitivity to underwater acoustic signals. Over the past century, scientists have designed many methods to investigate auditory capacity of fish. Behavioral training paradigms (with either punishment or reward as incentives to the tested subjects) and various electrophysiological meth-ods have been used to obtain audiograms, i.e., the auditory sensitivity curves of fish. Each method has its practical limitations: behavioral methods take long training time while the electrophysiological methods are invasive. This chapter first describes a novel, non-invasive electrophysiological recording method, i.e., the auditory brainstem response (ABR), which was first developed in my laboratory with the purpose of obtaining audiograms within short time for a comprehensive study on fish hearing ability. The setup of the system as well as technical details involved in using the ABR system are discussed in-depth with inputs from various users over the past 5 years since the debut of the ABR method. The second part of this chapter is focused on understanding how gas-holding structures (e.g., gasbladder, suprabranchial cham-ber, otic gasbladder) play a role in overall hearing ability of fish. The gas-holding structure, e.g., gasbladder, is generally regarded as an underwater resonant bubble. It is assumed that the resonant fre-quency created by the passing sound wave to gas-holding structure could aid in overall hearing ability o