Source levels of clicks from free-ranging white-beaked dolphins (Lagenorhynchus albirostris Gray 1846) recorded in Icelandic waters

Abstract

This study reports the source levels of clicks recorded from free-ranging white-beaked dolphins (Lagenorhynchus albirostris Gray 1846). A four-hydrophone array was used to obtain sound recordings. The hydrophone signals were digitized on-line and stored in a portable computer. An underwater video camera was used to visualize dolphins to help identify on-axis recordings. The range to a dolphin was calculated from differences in arrival times of clicks at the four hydrophones, allowing for calculations of source levels. Source levels in a single click train varied from 194 to 211 dB peak-to-peak (p-p) $\text{re:\hspace{0.17em}1\hspace{0.17em}μ}\mathrm{Pa}.$ The source levels varied linearly with the log of range. The maximum source levels recorded were 219 dB (p-p) $\text{re:\hspace{0.17em}1\hspace{0.17em}μ}\mathrm{Pa}.$