Department of Biology

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Professor Peter Teglberg Madsen

Energy compensation and received echo level dynamics in constant-frequency bats during active target approaches

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Energy compensation and received echo level dynamics in constant-frequency bats during active target approaches. / Stidsholt, Laura; Müller, Rolf; Beedholm, Kristian; Ma, Hui; Johnson, Mark; Madsen, Peter Teglberg.

In: Journal of Experimental Biology, Vol. 223, No. 2, jeb217109, 2020.

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@article{a7587a0e5ee641a5a42f28fa8975aefd,
title = "Energy compensation and received echo level dynamics in constant-frequency bats during active target approaches",
abstract = "Bats have been reported to adjust the energy of their outgoing vocalizations to target range (R) in a logarithmic fashion close to 20log10R which has been interpreted as providing one-way compensation for increasing echo levels during target approaches. However, it remains unknown how species using high-frequency calls, which are strongly affected by absorption, adjust their vocal outputs during approaches to point targets. We hypothesized that such species should compensate less than the 20log10R model predicts at longer distances and more at shorter distances as a consequence of the significant influence of absorption at longer ranges. Using a microphone array and an acoustic recording tag, we show that the output adjustments of two Hipposideros pratti and one Hipposideros armiger do not decrease logarithmically during approaches to different-sized targets. Consequently, received echo levels increase dramatically early in the approach phase with near-constant output levels, but level off late in the approach phase as a result of substantial output reductions. To improve echo-to-noise ratio, we suggest that bats using higher frequency vocalizations compensate less at longer ranges, where they are strongly affected by absorption. Close to the target, they decrease their output levels dramatically to mitigate reception of very high echo levels. This strategy maintains received echo levels between 6 and 40 dB re. 20 µPa2 s across different target sizes. The bats partially compensated for target size, but not in a one-to-one dB fashion, showing that these bats do not seek to stabilize perceived echo levels, but may instead use them to gauge target size.",
keywords = "Atmospheric absorption, CF bats, Echo level, Intensity compensation, Microphone array, Source level",
author = "Laura Stidsholt and Rolf M{\"u}ller and Kristian Beedholm and Hui Ma and Mark Johnson and Madsen, {Peter Teglberg}",
year = "2020",
doi = "10.1242/jeb.217109",
language = "English",
volume = "223",
journal = "BRITISH JOURNAL OF EXPERIMENTAL BIOLOGY",
issn = "0022-0949",
publisher = "The/Company of Biologists Ltd.",
number = "2",

}

RIS

TY - JOUR

T1 - Energy compensation and received echo level dynamics in constant-frequency bats during active target approaches

AU - Stidsholt, Laura

AU - Müller, Rolf

AU - Beedholm, Kristian

AU - Ma, Hui

AU - Johnson, Mark

AU - Madsen, Peter Teglberg

PY - 2020

Y1 - 2020

N2 - Bats have been reported to adjust the energy of their outgoing vocalizations to target range (R) in a logarithmic fashion close to 20log10R which has been interpreted as providing one-way compensation for increasing echo levels during target approaches. However, it remains unknown how species using high-frequency calls, which are strongly affected by absorption, adjust their vocal outputs during approaches to point targets. We hypothesized that such species should compensate less than the 20log10R model predicts at longer distances and more at shorter distances as a consequence of the significant influence of absorption at longer ranges. Using a microphone array and an acoustic recording tag, we show that the output adjustments of two Hipposideros pratti and one Hipposideros armiger do not decrease logarithmically during approaches to different-sized targets. Consequently, received echo levels increase dramatically early in the approach phase with near-constant output levels, but level off late in the approach phase as a result of substantial output reductions. To improve echo-to-noise ratio, we suggest that bats using higher frequency vocalizations compensate less at longer ranges, where they are strongly affected by absorption. Close to the target, they decrease their output levels dramatically to mitigate reception of very high echo levels. This strategy maintains received echo levels between 6 and 40 dB re. 20 µPa2 s across different target sizes. The bats partially compensated for target size, but not in a one-to-one dB fashion, showing that these bats do not seek to stabilize perceived echo levels, but may instead use them to gauge target size.

AB - Bats have been reported to adjust the energy of their outgoing vocalizations to target range (R) in a logarithmic fashion close to 20log10R which has been interpreted as providing one-way compensation for increasing echo levels during target approaches. However, it remains unknown how species using high-frequency calls, which are strongly affected by absorption, adjust their vocal outputs during approaches to point targets. We hypothesized that such species should compensate less than the 20log10R model predicts at longer distances and more at shorter distances as a consequence of the significant influence of absorption at longer ranges. Using a microphone array and an acoustic recording tag, we show that the output adjustments of two Hipposideros pratti and one Hipposideros armiger do not decrease logarithmically during approaches to different-sized targets. Consequently, received echo levels increase dramatically early in the approach phase with near-constant output levels, but level off late in the approach phase as a result of substantial output reductions. To improve echo-to-noise ratio, we suggest that bats using higher frequency vocalizations compensate less at longer ranges, where they are strongly affected by absorption. Close to the target, they decrease their output levels dramatically to mitigate reception of very high echo levels. This strategy maintains received echo levels between 6 and 40 dB re. 20 µPa2 s across different target sizes. The bats partially compensated for target size, but not in a one-to-one dB fashion, showing that these bats do not seek to stabilize perceived echo levels, but may instead use them to gauge target size.

KW - Atmospheric absorption

KW - CF bats

KW - Echo level

KW - Intensity compensation

KW - Microphone array

KW - Source level

UR - http://www.scopus.com/inward/record.url?scp=85078685124&partnerID=8YFLogxK

U2 - 10.1242/jeb.217109

DO - 10.1242/jeb.217109

M3 - Journal article

C2 - 31836651

AN - SCOPUS:85078685124

VL - 223

JO - BRITISH JOURNAL OF EXPERIMENTAL BIOLOGY

JF - BRITISH JOURNAL OF EXPERIMENTAL BIOLOGY

SN - 0022-0949

IS - 2

M1 - jeb217109

ER -