The Functional Organisation of the Auditory Cortex in the CF — FM Bat Rhinolophus ferrumequinum
Greater Horseshoe Bats, Rhinolophus ferrumequinum, use orientation sounds consisting of a long constant frequency (cf) part, followed by a short, downward frequency modulated (fm) part. By lowering their emission frequency during flight they compensate Dopplershifts and keep the cf-part of their echoes in a very small frequency band that is characteristic for each individual animal. Thereby they create a constant carrier frequency on which the fast, complex amplitude and frequency modulations are superimposed that are produced by the movements of targets, for instance the wingbeat of flying insects. Those modulations are characteristic for each insect species and size and may therefore be used to classify or even identify prey and to distinguish them from background clutter.
KeywordsCarrier Frequency Auditory Cortex Pure Tone Modulation Depth Background Clutter
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