Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Echolocation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed1980

[Effect of destruction of the inferior colliculi on the performance of the echolocating system of horseshoe-nosed bats].

The effect of unilateral and bilateral destruction of the inferior colliculi on the auditory system sensitivity, sonar signals' parameters and the Doppler shift compensation in echoes was studied in horseshoe bats Rhinolophus ferrumequinum. Complete bilateral destruction of the inferior colliculi did not produce the auditory system disfunction, but it sharply decreased auditory sensitivity of this system which was manifested in a reduction of the maximum detection range and inability to detect a weakly sounding insect. The data obtained suggest that the inferior colliculi are immediately responsible for the maintenance of emitting frequency and that the role which various regions of inferior colliculus play in that process is different. To preserve the effect of the Doppler shift compensation it is necessary to keep intact not less than a half of the central nucleus at least of one inferior colliculus.

Animals↗
PubMed1993

Neural computations for sound pattern recognition: evidence for summation of an array of frequency filters in an echolocating bat.

Microchiropteran bats use an auditory sonar system for orientation and prey capture. Many bats use highly structured constant-frequency (CF) and frequency-modulated (FM) sonar orientation signals. Mechanisms for sound pattern recognition are important for the perception of these and other types of auditory signals. The processing and recognition of FM sound components appears to be important for certain complex perceptual tasks, including target distance perception. I have conducted behavioral studies using artificial echoes to simulate the conditions of a bat flying toward a target. An innate vocalization response of the bat to the simulated approaching target was used to assess the ability of the bat to analyze the structure of and extract distance information from different types of synthetic FM sound patterns. The bat's performance depended on the structure of the artificial echo. The pattern recognition performance of the bats was similar when they were presented with either a naturally structured artificial CF/FM echo or an artificial CF/FM echo containing an FM component consisting of a series of pure tone steps. The ability of the bats to recognize appropriately the structure of an FM signal constructed from a sequence of pure tones depended on the number of pure tone steps in the series. Noctilio was able to recognize FM sound patterns containing 99 or greater pure tone steps. The minimum required number of pure tone steps could be distributed over different frequency ranges. The bats were able to resolve individual tone steps in the series that were separated by at least 100 Hz.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

[The structural characteristics of the echolocation signal in the beluga whale Delphinapterus leucas].

The sounding signal analysis of beluga dolphin under aquatory adaptation with orientation reflexes has been conducted. It has been shown that the single sounding orientation impulse of beluga has a complex structure. Its initial part consists of a large number of components and has a great power. The main part of impulse is frequency-modulated and has a large duration and constant amplitude. The spectral analysis of beluga's signal demonstrates the low-frequency character with spectrum maximal of 1.6 kHz.

Animals↗
PubMedDate not supplied

[Physiologic mechanisms of use of the Doppler effect in echolocation by Rhinolophus ferrumequinum bats].

During the flight, the greater horse-shoe bat R. ferrumequinum decreases the frequency in the medial part of the emmited signal in proportion to the relative target--bat velocity. The value of the decrease is approximately equal to the Doppler shift; as a result, the animal picks up the echo at its species specific frequency irrespectively of the flight velocity. Threshold curve of bat's auditory system plotted in terms of N4, exhibits a sharp turning peak with a slope of about 83 dB/kHz towards low frequencies. The species specific frequency lies between the frequencies corresponding to the highest and the lowest thresholds. The described peculiarities of emission and perception of signals allow to consider the orientation system in the bat as a Doppler compensating system which provides the effective detection and discrimination of moving targets (e.g., a prey), improves spatial characteristics of hearing and enables the animal to evaluate the velocity during approaching the target.

Animals↗