|Methodology and results of calibration of tonal click detectors for small odontocetes (C-PODs)|Dähne, M.; Verfuß, U.K.; Brandecker, A.; Siebert, U.; Benke, H. (2013). Methodology and results of calibration of tonal click detectors for small odontocetes (C-PODs). J. Acoust. Soc. Am. 134(3): 2514-2522. hdl.handle.net/10.1121/1.4816578
In: The Journal of the Acoustical Society of America. American Institute of Physics: New York, etc. ISSN 0001-4966, more
acoustic signal processing, calibration, hydrophones, regression analysis
|Authors|| || Top |
- Dähne, M.
- Verfuß, U.K.
- Brandecker, A.
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.