Source of the North Pacific "boing" sound attributed to minke whales.

During a recent cetacean survey of the U.S. waters surrounding the Hawaiian Islands, the probable source of the mysterious "boing" sound of the North Pacific Ocean was identified as a minke whale, Balaenoptera acutorostrata. Examination of boing vocalizations from three research surveys confirms previous work that identified two distinct boing vocalization types in the North Pacific. The eastern boing (n = 22) has a pulse repetition rate of 92 s(-1) and a duration of 3.6 s and was found only east of 138 degrees W. The central boing (n = 106) has a pulse repetition rate of 115 s(-1) and a duration of approximately 2.6 s and was found only west of 135 degrees W. Central boing vocalizations produced by a single source (n = 84) indicate that variation in repetition rate and duration of the calls of the individual were not significantly different than the variation among individuals of the same boing type. Despite a slight latitudinal overlap in the vocalizations, pulse repetition rates of the eastern and central boings were distinct.