title: Determining the detection thresholds for harbor porpoise clicks of autonomous data loggers, the Timing Porpoise Detectors.
abstract: Timing Porpoise Detectors (T-PODs, Chelonia Ltd.) are autonomous passive acoustic devices for monitoring odontocetes. They register the time of occurrence and duration of high frequency pulsed sounds as possible odontocetes echolocation clicks. Because of evolution, five T-POD versions exist. Although the manufacturer replaced those by a digital successor, the C-POD, T-PODs are still used, and data from many field studies exist. Characterizing the acoustic properties of T-PODs enables the interpretation of data obtained with different devices. Here, the detection thresholds of different T-POD versions for harbor porpoise clicks were determined. While thresholds among devices were quite variable in the first T-POD generations, they became more standardized in newer versions. Furthermore, the influence of user-controlled settings on the threshold was investigated. From version 3 on, the detection threshold was found to be easily adjustable with version-dependent setting options "minimum intensity" and "sensitivity," enabling the presetting of standard thresholds. In version 4, the setting "click bandwidth" had a strong influence on the detection threshold, while "selectivity" in version 3 and "noise adaptation = ON" or "OFF" in version 4 hardly influenced thresholds obtained in the tank tests. Nevertheless, the latter setting may influence thresholds in a complex acoustic environment like the sea.
authors: German Oceanographic Museum, Katharinenberg 14-20, 18439 Stralsund, Germany. ukv@smru.co.uk
authors: Ursula K
authors: UK
authors: Verfuß
authors: Michael
authors: M
authors: Dähne
authors: Anja
authors: A
authors: Gallus
authors: Martin
authors: M
authors: Jabbusch
authors: Harald
authors: H
authors: Benke
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D000818:Animals; D002138:Calibration; D004455:Echolocation; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D004867:Equipment Design; D006801:Humans; D008386:Marine Biology / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D009792:Oceans and Seas; D050741:Phocoena / Q000502:physiology* / Q000523:psychology; D012015:Reference Standards; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013997:Time Factors; D014159:Transducers; D014828:Vocalization, Animal