Guide to Constructing Hydrophones and Hydrophone Arrays for Monitoring Marine Mammal Vocalizations

摘要

This document provides a guide to building single hydrophones suitable for listening to and recording marine mammal vocalizations or linear hydrophone arrays in which several hydrophones are molded onto a single cable for localizing a sound source. This guide is intended for anyone with an interest in building hydrophones, and no special expertise is required. The hydrophones described below are based on an EC65 cylindrical hydrophone element (EDO Corporation Salt Lake City, Utah)1 and a low noise preamplifier. This combination has proven to be reliable, gives a very clean sound (up to approximately 40 kHz), and is excellent for receiving sounds from sperm whales, humpback whales, and several dolphin species. The preamp incorporates a high-pass filter that reduces flow noise that occurs when towing the hydrophones. A very small modification can be made to remove this filter and extend the usable frequency response down to a few Hz. Note that even with this modification, the hydrophones are not linear in frequency response. An example calibration is provided. Some sound analysis software can compensate for a known frequency response to restore linearity. The building process described here consists of many steps, none of which are difficult.