A model of echolocation of multiple targets in 3D space from a single emission.

Bats, using frequency-modulated echolocation sounds, can capture a moving target in real 3D space. The process by which they are able to accomplish this, however, is not completely understood. This work offers and analyzes a model for description of one mechanism that may play a role in the echolocation process of real bats. This mechanism allows for the localization of targets in 3D space from the echoes produced by a single emission. It is impossible to locate multiple targets in 3D space by using only the delay time between an emission and the resulting echoes received at two points (i.e., two ears). To locate multiple targets in 3D space requires directional information for each target. The frequency of the spectral notch, which is the frequency corresponding to the minimum of the external ear's transfer function, provides a crucial cue for directional localization. The spectrum of the echoes from nearly equidistant targets includes spectral components of both the interference between the echoes and the interference resulting from the physical process of reception at the external ear. Thus, in order to extract the spectral component associated with the external ear, this component must first be distinguished from the spectral components associated with the interference of echoes from nearly equidistant targets. In the model presented, a computation that consists of the deconvolution of the spectrum is used to extract the external-ear-dependent component in the time domain. This model describes one mechanism that can be used to locate multiple targets in 3D space.

[1]  R. Altes.  Angle estimation and binaural processing in animal echolocation. , 1978, The Journal of the Acoustical Society of America.

[2]  A. Lee Swindlehurst,et al.  Methods for blind equalization and resolution of overlapping echoes of unknown shape , 1999, IEEE Trans. Signal Process..

[3]  J. Simmons,et al.  Sound source elevation and external ear cues influence the discrimination of spectral notches by the big brown bat, Eptesicus fuscus. , 1996, The Journal of the Acoustical Society of America.

[4]  W. Sullivan,et al.  Neural representation of target distance in auditory cortex of the echolocating bat Myotis lucifugus. , 1982, Journal of neurophysiology.

[5]  Alan R. Palmer,et al.  Filtering Due to the Inner Hair-Cell Membrane Properties and its Relation to the Phase-Locking Limit in Cochlear Nerve Fibres , 1986 .

[6]  R. Altes.  Sonar for generalized target description and its similarity to animal echolocation systems. , 1976, The Journal of the Acoustical Society of America.

[7]  C F Moss,et al.  Spatially Selective Auditory Responses in the Superior Colliculus of the Echolocating Bat , 1997, The Journal of Neuroscience.

[8]  G. Schuller,et al.  Facilitation and Delay Sensitivity of Auditory Cortex Neurons in CF‐FM Bats, Rhinolophus rouxi and Pteronotus p.parnellii , 1991, The European journal of neuroscience.

[9]  Cynthia F. Moss,et al.  Composition of biosonar images for target recognition by echolocating bats , 1995, Neural Networks.

[10]  N Suga,et al.  Delay-tuned combination-sensitive neurons in the auditory cortex of the vocalizing mustached bat. , 1988, Journal of neurophysiology.

[11]  E Covey,et al.  Monaural interaction of excitation and inhibition in the medial superior olive of the mustached bat: an adaptation for biosonar. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[12]  N. Suga,et al.  Directional sensitivity of echolocation system in bats producing frequency-modulated signals. , 1974, The Journal of experimental biology.

[13]  J. E. Rose,et al.  Phase-locked response to low-frequency tones in single auditory nerve fibers of the squirrel monkey. , 1967, Journal of neurophysiology.

[14]  H Peremans,et al.  The spectrogram correlation and transformation receiver, revisited. , 1998, The Journal of the Acoustical Society of America.

[15]  J A Simmons,et al.  Echolocation in bats: the external ear and perception of the vertical positions of targets. , 1982, Science.

[16]  M. Fenton,et al.  Recognition of Species of Insectivorous Bats by Their Echolocation Calls , 1981 .

[17]  N. Suga,et al.  Neural axis representing target range in the auditory cortex of the mustache bat. , 1979, Science.

[18]  D. Hartley,et al.  The sound emission pattern of the echolocating bat, Eptesicus fuscus , 1989 .

[19]  J. Fritz,et al.  Tonotopic and functional organization in the auditory cortex of the big brown bat, Eptesicus fuscus. , 1993, Journal of neurophysiology.

[20]  James A. Simmons,et al.  Auditory Dimensions of Acoustic Images in Echolocation , 1995 .

[21]  R Müller,et al.  Acoustic flow perception in cf-bats: extraction of parameters. , 2000, The Journal of the Acoustical Society of America.

[22]  S. Liu,et al.  Novel method for super-resolution in radar range domain , 1999 .

[23]  Z. Fuzessery,et al.  Monaural and binaural spectral cues created by the external ears of the pallid bat , 1996, Hearing Research.

[24]  J. Simmons,et al.  Spectral cues and perception of the vertical position of targets by the big brown bat, Eptesicus fuscus. , 2000, The Journal of the Acoustical Society of America.

[25]  J. Simmons.  The resolution of target range by echolocating bats. , 1973, The Journal of the Acoustical Society of America.

[26]  N. Suga,et al.  Cortical neurons sensitive to combinations of information-bearing elements of biosonar signals in the mustache bat. , 1978, Science.

[27]  M Zeilik.  The Fajada Butte Solar Marker: A Reevaluation , 1985, Science.

[28]  J A Simmons,et al.  Neural responses to overlapping FM sounds in the inferior colliculus of echolocating bats. , 2000, Journal of neurophysiology.

[29]  James A. Simmons,et al.  A possible neuronal basis for representation of acoustic scenes in auditory cortex of the big brown bat , 1993, Nature.

[30]  J E Hind,et al.  Time structure of discharges in single auditory nerve fibers of the squirrel monkey in response to complex periodic sounds. , 1969, Journal of neurophysiology.

[31]  J. H. Casseday,et al.  Connections of the superior olivary complex in the rufous horseshoe bat Rhinolophus rouxi , 1988, The Journal of comparative neurology.

[32]  R. Kuc.  Sensorimotor model of bat echolocation and prey capture. , 1994, The Journal of the Acoustical Society of America.

[33]  J. H. Casseday,et al.  The monaural nuclei of the lateral lemniscus in an echolocating bat: parallel pathways for analyzing temporal features of sound , 1991, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[34]  J. Simmons.  A view of the world through the bat's ear: The formation of acoustic images in echolocation , 1989, Cognition.

[35]  J. Simmons,et al.  Spatially dependent acoustic cues generated by the external ear of the big brown bat, Eptesicus fuscus. , 1995, The Journal of the Acoustical Society of America.

[36]  J A Simmons,et al.  Sonar tracking of horizontally moving targets by the big brown bat Eptesicus fuscus. , 1985, Science.

[37]  J A Simmons,et al.  A computational model of echo processing and acoustic imaging in frequency-modulated echolocating bats: the spectrogram correlation and transformation receiver. , 1993, The Journal of the Acoustical Society of America.