Munger, L., D.K. Mellinger, S.M. Wiggins, S.E. Moore, and J.A. Hildebrand.
2005. Performance of spectrogram correlation in detecting right whale calls in
long-term recordings from the Bering Sea. Canadian Acoustics 33(2): 25-34.
ABSTRACT
We investigated the performance of spectrogram cross-correlation for
automatically detecting North Pacific right whale (Eubalaena japonica) calls in
long-term acoustic recordings from the southeastern Bering Sea. Data were
sampled by autonomous, bottom-mounted hydrophones deployed in the southeastern
Bering Sea from October 2000 through August 2002. A human analyst detected
right whale calls within the first month (October 2000) of recorded data by
visually examining spectrograms and by listening to recorded data; these manual
detections were then compared to results of automated detection trials.
Automated detection by spectrogram cross-correlation was implemented using a
synthetic kernel based on the most common right whale call type. To optimize
automated detection parameters, the analyst performed multiple trials on
minutes-long and hour-long recordings and manually adjusted detection
parameters between trials. A single set of optimized detection parameters was
used to process a week-long recording from October 2000. The automated detector
trials resulted in increasing proportions of false and missed detections with
increasing data set duration, due to the higher proportion of acoustic noise
and lower overall call rates in longer recordings. However, the automated
detector missed only one calling ?bout? (2 or more calls within a 10-minute
span) of the 18 bouts present in the week-long recording. Despite the high
number of false detections and missed individual calls, spectrogram
cross-correlation was useful to guide a human analyst to sections of data with
potential right whale calling bouts. Upon reviewing automatic detection events,
the analyst could quickly dismiss false detections and search recordings before
and after correct detections to find missed calls, thus improving the
efficiency of searching for a small number of calls in long-term (months- to
years-long) recordings.
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Please address any inquiries to
Thanks,
Lisa Munger
Scripps Institution of Oceanography
University of California, San Diego
La Jolla, CA 92093-0205
+1-858-534-5755
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