title: Neglect of bandwidth of Odontocetes echo location clicks biases propagation loss and single hydrophone population estimates.
abstract: Passive acoustic monitoring with a single hydrophone has been suggested as a cost-effective method to monitor population density of echolocating marine mammals, by estimating the distance at which the hydrophone is able to intercept the echolocation clicks and distinguish these from the background. To avoid a bias in the estimated population density, this method relies on an unbiased estimate of the detection range and therefore of the propagation loss (PL). When applying this method, it is common practice to estimate PL at the center frequency of a broadband echolocation click and to assume this narrowband PL applies also to the broadband click. For a typical situation this narrowband approximation overestimates PL, underestimates the detection range and consequently overestimates the population density by an amount that for fixed center frequency increases with increasing pulse bandwidth and sonar figure of merit.
authors.affiliation: Netherlands Organisation for Applied Scientific Research, P.O. Box 96864, 2509 JG, The Hague, Netherlands.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Ainslie
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D000818:Animals; D002591:Cetacea / Q000145:classification* / Q000502:physiology*; D004455:Echolocation / Q000145:classification*; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D009791:Oceanography / Q000295:instrumentation* / Q000379:methods; D009792:Oceans and Seas; D011156:Population Density; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013045:Species Specificity; D013550:Swimming; D014159:Transducers; D014828:Vocalization, Animal / Q000145:classification*