Communication breakdown: Limits of spectro-temporal resolution for the perception of bat communication calls
During vocal communication, the spectro‑temporal structure of vocalizations conveys important
contextual information. Bats excel in the use of sounds for echolocation by meticulous encoding of
signals in the temporal domain. We therefore hypothesized that for social communication as well,
bats would excel at detecting minute distortions in the spectro‑temporal structure of calls. To test
this hypothesis, we systematically introduced spectro‑temporal distortion to communication calls of
Phyllostomus discolor bats. We broke down each call into windows of the same length and randomized
the phase spectrum inside each window. The overall degree of spectro‑temporal distortion in
communication calls increased with window length. Modelling the bat auditory periphery revealed
that cochlear mechanisms allow discrimination of fast spectro‑temporal envelopes. We evaluated
model predictions with experimental psychophysical and neurophysiological data. We first assessed
bats’ performance in discriminating original versions of calls from increasingly distorted versions of
the same calls. We further examined cortical responses to determine additional specializations for
call discrimination at the cortical level. Psychophysical and cortical responses concurred with model
predictions, revealing discrimination thresholds in the range of 8–15 ms randomization‑window
length. Our data suggest that specialized cortical areas are not necessary to impart psychophysical
resilience to temporal distortion in communication calls.
contextual information. Bats excel in the use of sounds for echolocation by meticulous encoding of
signals in the temporal domain. We therefore hypothesized that for social communication as well,
bats would excel at detecting minute distortions in the spectro‑temporal structure of calls. To test
this hypothesis, we systematically introduced spectro‑temporal distortion to communication calls of
Phyllostomus discolor bats. We broke down each call into windows of the same length and randomized
the phase spectrum inside each window. The overall degree of spectro‑temporal distortion in
communication calls increased with window length. Modelling the bat auditory periphery revealed
that cochlear mechanisms allow discrimination of fast spectro‑temporal envelopes. We evaluated
model predictions with experimental psychophysical and neurophysiological data. We first assessed
bats’ performance in discriminating original versions of calls from increasingly distorted versions of
the same calls. We further examined cortical responses to determine additional specializations for
call discrimination at the cortical level. Psychophysical and cortical responses concurred with model
predictions, revealing discrimination thresholds in the range of 8–15 ms randomization‑window
length. Our data suggest that specialized cortical areas are not necessary to impart psychophysical
resilience to temporal distortion in communication calls.
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