Lateralized sound production in the beluga whale (Delphinapterus leucas)

Like other toothed whales, belugas produce sound through pneumatic actuation of two phonic lip pairs, but it is unclear whether both pairs are actuated concurrently to generate a single sound (the dual actuation hypothesis) or laterally in the production of their rich vocal repertoires. Here, using suction cup hydrophones on the head of a trained beluga whale, we measured seven different communication signal types and echolocation clicks in order to test the hypothesis that belugas produce distinct sounds unilaterally. We show that, like other delphinoids, belugas produce echolocation clicks with the right phonic lips and tonal sounds from the left. We also demonstrate for the first time that the left phonic lips are responsible for generating communication signals other than tonal sounds. Thus, our findings provide empirical support for functionalized laterality in delphinoid sound production, in keeping with the functional laterality hypothesis of vocal-motor control in toothed whales.