Tank acoustics substantially distort broadband sounds produced by marine crustaceans

Abstract

Marine crustaceans produce broadband sounds that have been mostly characterized in tanks. While tank physical impacts on such signals are documented in the acoustic community, they are overlooked in the bioacoustic literature with limited empirical comparisons. Here, we compared broadband sounds produced at 1 m from spiny lobsters ( Panulirus argus) in both tank and in situ conditions. We found significant differences in all sound features (temporal, power, and spectral) between tank and in situ recordings, highlighting that broadband sounds, such as those produced by marine crustaceans, cannot be accurately characterized in tanks. We then explained the three main physical impacts that distort broadband sounds in tanks, respectively known as resonant frequencies, sound reverberation, and low frequency attenuation. Tank resonant frequencies strongly distort the spectral shape of broadband sounds. In the high frequency band (above the tank minimum resonant frequency), reverberation increases sound duration. In the low frequency band (below the tank minimum resonant frequency), low frequencies are highly attenuated due to their longer wavelength compared to the tank size and tank wall boundary conditions (zero pressure) that prevent them from being accurately measured. Taken together, these results highlight the importance of understanding tank physical impacts when characterizing broadband crustacean sounds.

Vessel sound causes hearing loss for hummingbird bobtail squid (Euprymna berryi)

“…While there is some evidence of habituation to acoustic stimuli in cephalopods (Samson et al, 2016;Cones et al, 2022), most behavioural experiments on the effect of noise on aquatic life have been conducted in the laboratory where conditions can be controlled, and individuals observed. Yet, the caveats of working in a laboratory environment must be noted, as small experimental tanks have complex acoustic fields with overlapping reflection and refraction (Jeźequel et al, 2022). The sound exposure methodology used in this study was chosen to alleviate some of the complications of small tanks by placing the squid in a small arena within the experimental tank and calibrating at the location of the animal.…”

“…It is important to note that the difference between sound pressure and particle motion cannot be easily predicted in small tanks (Nedelec et al, 2016;Sisneros et al, 2016;Jeźequel et al, 2022). Therefore, prior to the start of each AEP trial, particle motion and sound pressure were calibrated at the position normally occupied by the experimental animal to allow audiograms to be produced for the two measures.…”