How to Build & Use Low-Cost Hydrophones. Contents follow: Listening to the Sea, Transducers, Cable, Hydrophone Preamplifiers, Hydrophone Containers, Hydrophone Deployment, Hydrophones for Towing, Power Amplifiers, Monitoring the Song of the Humpback Whale: An Historical Perspective, Appendices: 1. Bibliography, 2. Sources of Materials, and 3. Abbreviations and Symbols.