The energy ratio mapping algorithm (ERMA) was developed to improve the performance of
energy-based detection of odontocete echolocation clicks, especially for application in environments
with limited computational power and energy such as acoustic gliders. ERMA systematically
evaluates many frequency bands for energy ratio-based detection of echolocation clicks produced
by a target species in the presence of the species mix in a given geographic area. To evaluate the
performance of ERMA, a Teager-Kaiser energy operator was applied to the series of energy ratios
as derived by ERMA. A noise-adaptive threshold was then applied to the Teager-Kaiser function to
identify clicks in data sets. The method was tested for detecting clicks of Blainville’s beaked
whales while rejecting echolocation clicks of Risso’s dolphins and pilot whales. Results showed
that the ERMA-based detector correctly identified 81.6% of the beaked whale clicks in an extended
evaluation data set. Average false-positive detection rate was 6.3% (3.4% for Risso’s dolphins and
2.9% for pilot whales). VC 2011 Acoustical Society of America. [DOI: 10.1121/1.3531924