Evidence for a Decrease in Vocalizations During Bubble Burst Production in Atlantic Bottlenose Dolphins ( <i>Tursiops truncatus</i> )

ABSTRACT In Atlantic bottlenose dolphins, prior work has suggested that whistle vocalizations often have been observed to co‐occur with one bubble type, the bubble stream. However, vocal correlates have not been identified for another type of bubble, the bubble burst. While watching research session recordings, we serendipitously observed an absence of dolphin vocalization during bubble bursts. We formally investigated this in two studies by examining bubble bursts produced by 11 dolphins participating in various tasks with an exploratory study ( n = 553) and a preregistered, confirmatory study ( n = 150). In both studies, we compare the amplitude during the production of the bubble burst to the 2 s prior to its production, and the presence/absence of different vocal types. Amplitude during the bubble burst was significantly quieter than the 2 s prior, and there were significant reductions in all vocal types, especially among whistles and burst‐pulses, in both studies. Physiological evidence supports this phenomenon, since dolphin vocal production depends on pneumatic pressure in the nasal system, which may be relieved when the bubble burst is produced. However, testing in acoustically isolated conditions is necessary to confirm our observations. Aspects of the bubble burst itself, and its vocal suppression, may serve communicative purposes in dolphins.