My co-authors and I would like to provide
some information on our recent paper on the detection of complex sounds by
seals and sea lions. The goal of this
study was to test how auditory data predict detection of complex sounds in
quiet and noisy conditions. Our results
indicate that pinnipeds may utilize certain common features of natural sounds
to enhance detectability. We believe
that this study is relevant given current efforts to predict the effects of
anthropogenic noise on marine mammal species. Please let me know if you
have any comments or questions.
Thank You,
Kane Cunningham
--
“Auditory sensitivity of seals and sea
lions in complex listening scenarios.”
Cunningham, K. A., Southall, B. L.,
& Reichmuth, C.
Abstract
Standard
audiometric data, such as audiograms and critical ratios, are often used to
inform marine mammal noise-exposure criteria. However, these measurements are
obtained using simple, artificial stimuli—i.e., pure tones and flat-spectrum
noise—while natural sounds typically have more complex structure. In this
study, detection thresholds for complex signals were measured in (I) quiet and
(II) masked conditions for one California sea lion (Zalophus californianus )
and one harbor seal (Phoca vitulina ). In Experiment I, detection thresholds in
quiet conditions were obtained for complex signals designed to isolate three
common features of natural sounds: Frequency modulation, amplitude modulation,
and harmonic structure. In Experiment II, detection thresholds were obtained
for the same complex signals embedded in two types of masking noise: Synthetic
flat-spectrum noise and recorded shipping noise. To evaluate how accurately
standard hearing data predict detection of complex sounds, the results of Experiments
I and II were compared to predictions based on subject audiograms and critical
ratios combined with a basic hearing model.
Both subjects exhibited greater-than-predicted sensitivity to harmonic
signals in quiet and masked conditions, as well as to frequency-modulated
signals in masked conditions. These differences indicate that the complex
features of naturally occurring sounds enhance detectability relative to simple
stimuli.
The Journal of the Acoustical Society
of America, 136(6), 3410-3421 (2014).
--
Kane Cunningham
Pinniped Cognition and Sensory Systems Laboratory
e: kaacunni@ucsc.edu