The performance of methods based on the fractional Fourier transform for detecting marine mammal vocalizations

Locke, Jonathan D. and White, P.R. (2011) The performance of methods based on the fractional Fourier transform for detecting marine mammal vocalizations. Journal of the Acoustical Society of America, 130 (4), 1974-1984. (doi:10.1121/1.3631664).

Record type: Article

Abstract

The analysis of cetacean vocalizations is considered using Fourier-based techniques that employ
chirp functions in their decomposition. In particular, the paper considers a short-time methods
based on the fractional Fourier transform for detecting frequency modulated narrow-band signals,
such as dolphin whistles, and compares this to the classical short-time Fourier methods. The fractional
Fourier technique explored computes transforms associated with a range of chirp rates and
automatically selects the rate for the final analysis. This avoids the need for prior knowledge of signal’s
chirp rate. An analysis is presented that details the performance of both methods as signal
detectors and allows one to determine their detection thresholds. These thresholds are then used to
measure the detectability of synthetic signals. This principle is then extended to measure performance
on a set of recordings of narrow-band vocalizations from a range of cetacean species.

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