title: Acoustic discrimination between harbor porpoises and delphinids by using a simple two-band comparison.
abstract: A simple discrimination method between Delphinidae and Phocoenidae based on the comparison of the intensity ratios of two band frequencies (130 and 70 kHz) is proposed. Biosonar signals were recorded at the Istanbul Strait (Bosphorus) in Turkey. Simultaneously, the presence of the species was confirmed by visual observation. Two types of thresholds of two-band intensity ratios, fixed and dynamic threshold, were tested for identification. The correct detection and false alarm rates for porpoises were 0.55 and 0.06 by using the fixed threshold and 0.74 and 0.08 by using the dynamic threshold, respectively. When the dynamic threshold was employed, the appropriate threshold changed depending on the mix ratio of recorded sounds from both Delphinidae and Phocoenidae. Even under biased mix ratios from 26% to 82%, the dynamic threshold worked with >0.80 correct detection and <0.20 false alarm rates, whereas the fixed threshold did not. The proposed method is simple but quantitative, which can be applicable for any broadband recording system, including a single hydrophone with two frequency band detectors.
authors.affiliation: Graduate School of Informatics, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Saho
authors.initials: S
authors.lastname: Kameyama
authors.affiliation: National Research Institute of Fisheries Engineering, Hasaki, Kamisu, Ibaraki 314-0408, Japan.
authors.forename: Tomonari
authors.initials: T
authors.lastname: Akamatsu
authors.affiliation: Faculty of Fisheries, Istanbul University, Ordu Cad, No. 200, Laleli, Istanbul, Turkey.
authors.forename: Ayhan
authors.initials: A
authors.lastname: Dede
authors.affiliation: Faculty of Fisheries, Istanbul University, Ordu Cad, No. 200, Laleli, Istanbul, Turkey.
authors.forename: Ayaka Amaha
authors.initials: AA
authors.lastname: Öztürk
authors.affiliation: Field Science Education and Research Center, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Arai