Acoustic signals are critical for inter-and intraspecific communication in many animals. In bony fishes, sound production is widespread and is used in a variety of speciesspecific behaviors such as agonistic interactions and reproduction (see Lobel, 1992;Zelick et al., 1999;Myrberg and Fuiman, 2002). Acoustic cues can provide information on mate location, reproductive readiness to synchronize gamete release, size, aggression level, territory quality, fitness, and species or individual identity (Myrberg and Riggio, 1985;Myrberg et al., 1986;Myrberg et al., 1993;Kenyon, 1994;Lobel and Mann, 1995;Myrberg, 1997;Lobel, 2001;Myrberg and Stadler, 2002). Thus, identification and characterization of both biologically relevant acoustic signals and the response properties of the auditory system are important to understand the function and evolution of acoustic communication in fishes.Acoustic communication involves the transmission of information by a sender to a receiver with potential benefits to both individuals (Bradbury and Vehrencamp, 1998). In this case, natural selection should favor the production of sounds with frequency spectra and energy content that match the hearing abilities of the intended receiver, and vice versa. This sensory drive model of signal evolution assumes that sender and receiver coevolve within specific constraints of the environment (e.g. background noise and transmission properties) (Endler, 1992). However, few studies on fishes examine both sound production and hearing ability within a single species to test for adaptive coupling of sender signal production and receiver signal reception. Hearing sensitivity was found to match the characteristics of sounds produced in the frequency domain in some species, but a mismatch was observed in others (Cohen and Winn, 1967;Myrberg and Spires, 1980;Fine, 1981;Schellart and Popper, 1992;Ladich and Yan, 1998;Yan et al., 2000;Ladich, 2000). As a result, enhanced intraspecific acoustic communication may not be the main driving force for the evolution of accessory hearing structures because there is no clear relationship between frequency spectra of fish sounds and auditory sensitivity among species with Weberian ossicles, suprabranchial chambers and auditory bullae that serve to increase or modify hearing ability (Ladich, 1999; Ladich, 2000).Sounds provide important signals for inter-and intraspecific communication in fishes, but few studies examine fish acoustic behavior in the context of coevolution of sound production and hearing ability within a species. This study characterizes the acoustic behavior in a reproductive population of the Hawaiian sergeant fish, Abudefduf abdominalis, and compares acoustic features to hearing ability, measured by the auditory evoked potential (AEP) technique. Sergeant fish produce sounds at close distances to the intended receiver (р1-2 body lengths), with different pulse characteristics that are associated primarily with aggression, nest preparation and courtship-female-visit behaviors. Energy peaks of all sounds were be...

Sounds provide important signals for inter- and intraspecific communication in fishes, but few studies examine behavioral contexts of sound production and hearing ability within a single species. This study characterized the sounds and their behavioral contexts in a wild population of Hawaiian sergeant damselfishes (Abudefduf abdominalis), and compared their features to hearing sensitivity measured by both auditory-evoked potentials (AEP) and single-cell recordings in the auditory midbrain. The sergeant fish produces low intensity (∼85–115 dB rms re: 1 μPa), low-frequency (∼100–400 Hz) sounds during nest preparation, courtship an agonistic interactions. Both AEP and single-cell recordings show that fish are most sensitive to these frequencies (80–300 Hz) with best frequency at 100 Hz. However, auditory thresholds to tonal stimuli were approximately 20 dB lower for single-cell recordings than those measured by AEP experiments. Further, midbrain auditory neurons were on average more sensitive to playbacks of conspecific sounds than to pure tones. These experiments show that the hearing ability of this damselfish closely matches the intensity and spectral characteristics of sounds produced in the wild. Multidimensional studies that incorporate analyses of and responses to biologically relevant natural sounds are necessary to understand acoustic processing and the evolution of acoustic communication in fishes.