A small telemetry device, called a ‘‘vocalight,’’ was designed for attachment to a dolphin’s head using a suction cup. The vocalight lights up a variable number of light‐emitting diodes depending upon the loudness of sounds received at a hydrophone within the suction cup. If vocalights matched for sensitivity are put on each dolphin within a captive group, observers can identify which dolphin produces a vocalization. Use of vocalights indicates that source levels of whistles from captive bottlenosed dolphins,Tursiopstruncatus, range from approximately 125 to over 140 dBre: 1 μPa at 1 m.