Uwe Firzlaff

Gerd Schuller10
Susanne Hoffmann9
10Gerd Schuller
9Susanne Hoffmann
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The directional dependence of sound pressure transformation of head and pinna has been measured in the phyllostomid bat Phyllostomus discolor for the frontal hemisphere using a maximum length sequence method. The azimuthal position of the axis of highest pinna gain came closer to the midsagital plane with increasing frequency. The acoustic axis of highest(More)
Bats quickly navigate through a highly structured environment relying on echolocation. Large natural objects in the environment, like bushes or trees, produce complex stochastic echoes, which can be characterized by the echo roughness. Previous work has shown that bats can use echo roughness to classify the stochastic properties of natural objects. This(More)
Humans reliably recognize spoken vowels despite the variability of the sounds caused by the across-subject variability of the speakers' vocal tract. The vocal tract serves as a resonator which imprints a spectral envelope onto the sounds generated by the vocal folds. This spectral envelope contains not only information about the type of vocalization but(More)
Echolocating bats can identify three-dimensional objects exclusively through the analysis of acoustic echoes of their ultrasonic emissions. However, objects of the same structure can differ in size, and the auditory system must achieve a size-invariant, normalized object representation for reliable object recognition. This study describes both the(More)
BACKGROUND Many bats vocalizing through their nose carry a prominent noseleaf that is involved in shaping the emission beam of these animals. To our knowledge, the exact role of these appendages has not been thoroughly investigated as for no single species both the hearing and the emission spatial sensitivities have been obtained. In this paper, we set out(More)
The head-related transfer function (HRTF) has been measured in two CF/FM bats, Pteronotus parnellii and Rhinolophus rouxi from 575 positions in the frontal hemisphere. P. parnellii showed an increase of the elevation angle of the axis of highest pinna gain with increasing frequency followed by a specific decrease at 75 kHz. Such a drop of elevation angle of(More)
Absolute hearing thresholds in the spear-nosed bat Phyllostomus discolor have been determined both with psychophysical and neurophysiological methods. Neurophysiological data have been obtained from two different structures of the ascending auditory pathway, the inferior colliculus and the auditory cortex. Minimum auditory thresholds of neurons are very(More)
BACKGROUND The mammalian auditory cortex can be subdivided into various fields characterized by neurophysiological and neuroarchitectural properties and by connections with different nuclei of the thalamus. Besides the primary auditory cortex, echolocating bats have cortical fields for the processing of temporal and spectral features of the echolocation(More)
Rhinolophidae or Horseshoe bats emit long and narrowband calls. Fluttering insect prey generates echoes in which amplitude and frequency shifts are present, i.e. glints. These glints are reliable cues about the presence of prey and also encode certain properties of the prey. In this paper, we propose that these glints, i.e. the dominant glints, are also(More)
Echolocating bats can recognize 3-D objects exclusively through the analysis of the reflections of their ultrasonic emissions. For objects of small size, the spectral interference pattern of the acoustic echoes encodes information about the structure of an object. For some naturally occurring objects such as, e.g., flowers, the interference pattern as well(More)