{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T02:47:49Z","timestamp":1768790869365,"version":"3.49.0"},"reference-count":36,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2023,4,6]],"date-time":"2023-04-06T00:00:00Z","timestamp":1680739200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Recovery and Resilience Plan (NRRP)","award":["3138"],"award-info":[{"award-number":["3138"]}]},{"name":"National Recovery and Resilience Plan (NRRP)","award":["3175"],"award-info":[{"award-number":["3175"]}]},{"name":"National Recovery and Resilience Plan (NRRP)","award":["LIFE18NAT\/IT\/000942"],"award-info":[{"award-number":["LIFE18NAT\/IT\/000942"]}]},{"name":"European Union\u2014NextGenerationEU","award":["3138"],"award-info":[{"award-number":["3138"]}]},{"name":"European Union\u2014NextGenerationEU","award":["3175"],"award-info":[{"award-number":["3175"]}]},{"name":"European Union\u2014NextGenerationEU","award":["LIFE18NAT\/IT\/000942"],"award-info":[{"award-number":["LIFE18NAT\/IT\/000942"]}]},{"name":"LIFE Financial Instrument of the European Community, Life Delfi Project\u2014Dolphin Experience","award":["3138"],"award-info":[{"award-number":["3138"]}]},{"name":"LIFE Financial Instrument of the European Community, Life Delfi Project\u2014Dolphin Experience","award":["3175"],"award-info":[{"award-number":["3175"]}]},{"name":"LIFE Financial Instrument of the European Community, Life Delfi Project\u2014Dolphin Experience","award":["LIFE18NAT\/IT\/000942"],"award-info":[{"award-number":["LIFE18NAT\/IT\/000942"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Passive acoustics are widely used to monitor the presence of dolphins in the marine environment. This study aims to introduce a low-cost and homemade approach for assembling a complete underwater microphone (i.e., the hydrophone), employing cheap and easy to obtain components. The hydrophone was assembled with two piezo disks connected in a balanced configuration and encased in a plastic container filled with plastic foam. The hydrophone\u2019s performance was validated by direct comparison with the commercially available AS-1 hydrophone (Aquarian Hydrophones, Anacortes, U.S.) on different underwater acoustic signals: artificial acoustic signals (ramp and multitone signals) and various dolphin vocalizations (whistle, echolocation clicks, and burst pulse signals). The sensitivity of the device\u2019s performance to changes in the emission source position was also tested. The results of the validation procedure on both artificial signals and real dolphin vocalizations showed that the significant cost savings associated with cheap technology had a minimal effect on the recording device\u2019s performance within the frequency range of 0\u201335 kHz. At this stage of experimentation, the global cost of the hydrophone could be estimated at a few euros, making it extremely price competitive when compared to more expensive commercially available models. In the future, this effective and low-cost technology would allow for continuous monitoring of the presence of free-ranging dolphins, significantly lowering the total cost of autonomous monitoring systems. This would permit broadening the monitored areas and creating a network of recorders, thus improving the acquisition of data.<\/jats:p>","DOI":"10.3390\/rs15071946","type":"journal-article","created":{"date-parts":[[2023,4,6]],"date-time":"2023-04-06T03:59:55Z","timestamp":1680753595000},"page":"1946","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["The Development of a Low-Cost Hydrophone for Passive Acoustic Monitoring of Dolphin\u2019s Vocalizations"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9438-4791","authenticated-orcid":false,"given":"Rocco","family":"De Marco","sequence":"first","affiliation":[{"name":"Institute of Biological Resources and Marine Biotechnology (IRBIM), National Research Council (CNR), 60125 Ancona, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5362-3776","authenticated-orcid":false,"given":"Francesco","family":"Di Nardo","sequence":"additional","affiliation":[{"name":"Dipartimento di Ingegneria dell\u2019Informazione, Universit\u00e0 Politecnica delle Marche, 60131 Ancona, Italy"}]},{"given":"Alessandro","family":"Lucchetti","sequence":"additional","affiliation":[{"name":"Institute of Biological Resources and Marine Biotechnology (IRBIM), National Research Council (CNR), 60125 Ancona, Italy"},{"name":"National Biodiversity Future Center, 90133 Palermo, Italy"}]},{"given":"Massimo","family":"Virgili","sequence":"additional","affiliation":[{"name":"Institute of Biological Resources and Marine Biotechnology (IRBIM), National Research Council (CNR), 60125 Ancona, Italy"}]},{"given":"Andrea","family":"Petetta","sequence":"additional","affiliation":[{"name":"Institute of Biological Resources and Marine Biotechnology (IRBIM), National Research Council (CNR), 60125 Ancona, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6093-6570","authenticated-orcid":false,"given":"Daniel","family":"Li Veli","sequence":"additional","affiliation":[{"name":"Institute of Biological Resources and Marine Biotechnology (IRBIM), National Research Council (CNR), 60125 Ancona, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4765-8427","authenticated-orcid":false,"given":"Laura","family":"Screpanti","sequence":"additional","affiliation":[{"name":"Dipartimento di Ingegneria dell\u2019Informazione, Universit\u00e0 Politecnica delle Marche, 60131 Ancona, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8802-2164","authenticated-orcid":false,"given":"Veronica","family":"Bartolucci","sequence":"additional","affiliation":[{"name":"Dipartimento di Ingegneria dell\u2019Informazione, Universit\u00e0 Politecnica delle Marche, 60131 Ancona, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9346-2113","authenticated-orcid":false,"given":"David","family":"Scaradozzi","sequence":"additional","affiliation":[{"name":"Dipartimento di Ingegneria dell\u2019Informazione, Universit\u00e0 Politecnica delle Marche, 60131 Ancona, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2023,4,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1016\/j.marpolbul.2011.04.038","article-title":"Listening to the Deep: Live monitoring of ocean noise and cetacean acoustic signals","volume":"63","author":"Zaugg","year":"2011","journal-title":"Mar. 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