The Development of a Low-Cost Hydrophone for Passive Acoustic Monitoring of Dolphin’s Vocalizations

Passive acoustics are widely used to monitor the presence of dolphins in marine environment. This study aims introduce a low-cost and homemade approach for assembling complete underwater microphone (i.e., hydrophone), employing cheap easy obtain components. The hydrophone was assembled with two piezo disks connected balanced configuration encased plastic container filled foam. hydrophone’s performance validated by direct comparison commercially available AS-1 (Aquarian Hydrophones, Anacortes, U.S.) on different acoustic signals: artificial signals (ramp multitone signals) various dolphin vocalizations (whistle, echolocation clicks, burst pulse signals). sensitivity device’s changes emission source position also tested. results validation procedure both real showed that significant cost savings associated technology had minimal effect recording within frequency range 0–35 kHz. At this stage experimentation, global could be estimated at few euros, making it extremely price competitive when compared more expensive models. In future, effective would allow continuous monitoring free-ranging dolphins, significantly lowering total autonomous systems. permit broadening monitored areas creating network recorders, thus improving acquisition data.