Application of a diver‐operated 4‐channel acoustic/video recording device to study wild dolphin echolocation and communication

Despite decades of research on captive dolphins, there still is much to learn about dolphin echolocation and communication in the wild. This is mainly due to the difficulties associated with recording dolphin signals accurately in the wild, such as their broadband (with frequencies over 200 kHz) and directional nature, the difficulty of identifying vocalizing dolphins, and being confined to equipment aboard a vessel. To resolve these difficulties, an underwater portable battery‐operated digital recording device was developed that is capable of simultaneously capturing acoustic signals up to 220 kHz on 4 channels as well as video. It consists of a custom‐made underwater housing, containing two batteries, a digital camcorder, and an acoustic recording unit with signal conditioning board, 4‐channel data acquisition card, PC/104‐plus single board computer and power supply, and a notebook hard disk. Attached to the housing is a 4‐hydrophone star array. Post‐recording, acoustic signals recorded within 15 m are ...