No abstract

Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

No abstract

This paper describes a method for real-time, autonomous, joint detection-classification of humpback whale vocalizations. The approach adapts the spectrogram correlation method used by Mellinger and Clark [J. Acoust. Soc. Am. 107, 3518-3529 (2000)] for bowhead whale endnote detection to the humpback whale problem. The objective is the implementation of a system to determine the presence or absence of humpback whales with passive acoustic methods and to perform this classification with low false alarm rate in real time. Multiple correlation kernels are used due to the diversity of humpback song. The approach also takes advantage of the fact that humpbacks tend to vocalize repeatedly for extended periods of time, and identification is declared only when multiple song units are detected within a fixed time interval. Humpback whale vocalizations from Alaska, Hawaii, and Stellwagen Bank were used to train the algorithm. It was then tested on independent data obtained off Kaena Point, Hawaii in February and March of 2009. Results show that the algorithm successfully classified humpback whales autonomously in real time, with a measured probability of correct classification in excess of 74% and a measured probability of false alarm below 1%.

Observations of intensity fluctuations for broadband, 400-Hz multipath arrivals observed during the 1996 New England shelfbreak PRIMER study are described. Acoustic signals were generated by two bottom-mounted sources located on the continental slope in roughly 290-m water depth and were received on a 52-m-long vertical-line-array (VLA) located in 93-m water depth. Propagation ranges were 42.2 and 59.6 km. The bathymetry, oceanography, and bottom geology of the PRIMER site are described. Acoustic observables of point intensity, peak intensity, and integrated energy over the VLA are treated in terms of the scintillation index, log-intensity variance, and intensity probability density functions (PDFs). Variability of the observables are decomposed into high and low frequency components with time scales less than and greater than 2 h, to facilitate correlation to ocean processes at different timescales. Parabolic equation numerical simulations using a quasi-random undular tidal bore model are able to reproduce many of the observed intensity fluctuation to within a factor of 2, and they allow investigation of scintillation behavior as a function of range.