Learn More
Matched-field processing (MFP) and global inversion techniques have been applied to vocalizations from four whales recorded on a 48-element tilted vertical array off the Channel Islands in 1996. Global inversions from selected whale calls using as few as eight elements extracted information about the surrounding ocean bottom composition, array shape, and(More)
Conventional detection of humpback vocalizations is often based on frequency summation of band-limited spectrograms under the assumption that energy (square of the Fourier amplitude) is the appropriate metric. Power-law detectors allow for a higher power of the Fourier amplitude, appropriate when the signal occupies a limited but unknown subset of these(More)
Passive acoustic monitoring of marine mammal calls is an increasingly important method for assessing population numbers, distribution, and behavior. A common mistake in the analysis of marine mammal acoustic data is formulating conclusions about these animals without first understanding how environmental properties such as bathymetry, sediment properties,(More)
This paper demonstrates the importance of accounting for environmental effects on passive underwater acoustic monitoring results. The situation considered is the reduction in shipping off the California coast between 2008-2010 due to the recession and environmental legislation. The resulting variations in ocean noise change the probability of detecting(More)
Time difference of arrival (TDOA) methods for acoustically localizing multiple marine mammals have been applied to recorded data from the Navy's Pacific Missile Range Facility in order to localize and track humpback whales. Modifications to established methods were necessary in order to simultaneously track multiple animals on the range faster than(More)
The maneuverability of autonomous underwater vehicles (AUVs) equipped with hull-mounted arrays provides the opportunity to actively modify received acoustic fields to optimize extraction of information. This paper uses ocean acoustic data collected by an AUV-mounted two-dimensional hydrophone array, with overall dimension one-tenth wavelength at 200-500 Hz,(More)
This paper describes the characteristics of an underwater biological chorus recorded in the midfrequency band (1-10 kHz) in the Southern California Bight. The recordings were made in July, 2002 by a large-vertical-aperture, 131-element, 2D billboard array. The chorus, observed predominantly on two consecutive nights during the 8-day experiment, is composed(More)
Waveguide propagation often displays transitions from one type of propagation to another as the mode number (or the takeoff angle from a ray theory point of view) increases. An example of such a transition occurs when the boundary of the waveguide changes from being formed by refraction to being formed by reflection. When these transitions occur, they can(More)
The purpose of this project is to apply physics-based signal and array processing techniques, recently developed in the area of underwater acoustics, to atmospheric infrasound data and co-located seismic field data. The source of the infrasound data is the newly installed International Monitoring System (IMS) infrasound station at Pinon Flat (PFO). The(More)
During the coordinated Philippine Sea 2009 experiment, conducted by the North Pacific Acoustic Laboratory working group, a 200m towed array (the ONR Five Octave Research Array) was used to measure signals and noise in deep water in the Philippine Sea. Broadband transmissions (225–325 Hz, 135-s LFM) were recorded from a Webb Research Corporation (WRC)(More)
  • 1