Human echolocators adjust loudness and number of clicks for detection of reflectors at various azimuth angles

L. Thaler, R. De Vos, D. Kish, M. Antoniou, C. Baker, M.C.J. Hornikx

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Uittreksel

In bats it has been shown that they adjust their emissions to situational demands. Here we report similar findings for human echolocation. We asked eight blind expert echolocators to detect reflectors positioned at various azimuth angles. The same 17.5 cm diameter circular reflector placed at 100 cm distance at 0°, 45° or 90° with respect to straight ahead was detected with 100% accuracy, but performance dropped to approximately 80% when it was placed at 135° (i.e. somewhat behind) and to chance levels (50%) when placed at 180° (i.e. right behind). This can be explained based on poorer target ensonification owing to the beampattern ofhumanmouth clicks. Importantly, analyses of sound recordings showthat echolocators increased loudness and numbers of clicks for reflectors at farther angles. Echolocatorswere able to reliably detect reflectors when level differences between echo and emission were as lowas 227 dB, which is much lower than expected based on previous work. Increasing intensity and numbers of clicks improves signal-to-noise ratio and in this way compensates for weaker target reflections. Our results are, to our knowledge, the first to show that human echolocation experts adjust their emissions to improve sensorysampling.Animplication fromour findings is that human echolocators accumulate information from multiple samples.

TaalEngels
Artikelnummer20172735
Aantal pagina's8
TijdschriftProceedings of the Royal Society B: Biological Sciences
Volume285
Nummer van het tijdschrift1873
DOI's
StatusGepubliceerd - 28 feb 2018

Vingerafdruk

Sound recording
Echolocation
azimuth
echolocation
Signal to noise ratio
Signal-To-Noise Ratio
bat
signal-to-noise ratio
Chiroptera
loudness
detection
sampling

Trefwoorden

    Citeer dit

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    abstract = "In bats it has been shown that they adjust their emissions to situational demands. Here we report similar findings for human echolocation. We asked eight blind expert echolocators to detect reflectors positioned at various azimuth angles. The same 17.5 cm diameter circular reflector placed at 100 cm distance at 0°, 45° or 90° with respect to straight ahead was detected with 100{\%} accuracy, but performance dropped to approximately 80{\%} when it was placed at 135° (i.e. somewhat behind) and to chance levels (50{\%}) when placed at 180° (i.e. right behind). This can be explained based on poorer target ensonification owing to the beampattern ofhumanmouth clicks. Importantly, analyses of sound recordings showthat echolocators increased loudness and numbers of clicks for reflectors at farther angles. Echolocatorswere able to reliably detect reflectors when level differences between echo and emission were as lowas 227 dB, which is much lower than expected based on previous work. Increasing intensity and numbers of clicks improves signal-to-noise ratio and in this way compensates for weaker target reflections. Our results are, to our knowledge, the first to show that human echolocation experts adjust their emissions to improve sensorysampling.Animplication fromour findings is that human echolocators accumulate information from multiple samples.",
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    Human echolocators adjust loudness and number of clicks for detection of reflectors at various azimuth angles. / Thaler, L.; De Vos, R.; Kish, D.; Antoniou, M.; Baker, C.; Hornikx, M.C.J.

    In: Proceedings of the Royal Society B: Biological Sciences, Vol. 285, Nr. 1873, 20172735, 28.02.2018.

    Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelWetenschappelijkpeer review

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    AU - De Vos,R.

    AU - Kish,D.

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    AU - Baker,C.

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