title: Methodology and results of calibration of tonal click detectors for small odontocetes (C-PODs).
abstract: Static acoustic monitoring (SAM) is one major technology for observing small cetacean species. Automatic click loggers deployed for long time periods (>2 months) with a single hydrophone are a standard solution. Acoustic properties, like detection thresholds of these instruments, are essential for interpretation of results, but have nevertheless received little attention. A methodology for calibrating tonal click detectors in small tanks consisting of the determination of the horizontal directivity pattern and detection thresholds including a transfer function is presented. Two approaches were tested to determine detection thresholds by (a) determining the 50% detection threshold and (b) fitting a linear regression model to the recorded relative amplitudes. The tests were carried out on C-PODs (Cetacean PODs, tonal click detectors), the most commonly used instrument for SAM in Europe. Directivity and threshold were tested between 60 and 150 kHz. Directivity showed a maximum variation of 8.5 dB in the horizontal plane. Sensitivity is highest between 80 and 130 kHz and linear (± 3 dB) in this frequency range for most of the instruments tested. C-PODs have a detection threshold (calculated with the linear model) of 114.5 ± 1.2 (standard deviation) dB re 1 μPa peak-peak at 130 kHz.
authors: German Oceanographic Museum, Katharinenberg 14-20, 18439 Stralsund, Germany. michael.daehne@tiho-hannover.de
authors: Michael
authors: M
authors: Dähne
authors: Ursula
authors: U
authors: Katharina Verfuß
authors: Anja
authors: A
authors: Brandecker
authors: Ursula
authors: U
authors: Siebert
authors: Harald
authors: H
authors: Benke
mesh_terms: D000162:Acoustics / Q000295:instrumentation; D000818:Animals; D049628:Body Size; D002138:Calibration; D002591:Cetacea / Q000145:classification / Q000502:physiology* / Q000523:psychology; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D004867:Equipment Design; D016014:Linear Models; D008386:Marine Biology / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D009792:Oceans and Seas; D010363:Pattern Recognition, Automated; D011156:Population Density; D012015:Reference Standards; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013550:Swimming; D013997:Time Factors; D014159:Transducers; D014828:Vocalization, Animal