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Echolocating bats must process temporal streams of sonar sounds to represent objects along the range axis. Neuronal echo-delay tuning, the putative mechanism of sonar ranging, has been characterized in the inferior colliculus (IC) of the mustached bat, an insectivorous species that produces echolocation calls consisting of constant frequency and frequency modulated (FM) components, but not in species that use FM signals alone. This raises questions about the mechanisms that give rise to echo-delay tuning in insectivorous bats that use different signal designs. To investigate whether stimulus context may account for species differences in echo-delay selectivity, we characterized single-unit responses in the IC of awake passively listening FM bats, Eptesicus fuscus, to broadcasts of natural sonar call-echo sequences, which contained dynamic changes in signal duration, interval, spectrotemporal structure, and echo-delay. In E. fuscus, neural selectivity to call-echo delay emerges in a population of IC neurons when stimulated with call-echo pairs presented at intervals mimicking those in a natural sonar sequence. To determine whether echo-delay selectivity also depends on the spectrotemporal features of individual sounds within natural sonar sequences, we studied responses to computer-generated echolocation signals that controlled for call interval, duration, bandwidth, sweep rate, and echo-delay. A subpopulation of IC neurons responded selectively to the combination of the spectrotemporal structure of natural call-echo pairs and their temporal patterning within a dynamic sonar sequence. These new findings suggest that the FM bat’s fine control over biosonar signal parameters may modulate IC neuronal selectivity to the dimension of echo-delay.
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Reconstruction of ultrasound signals using randomly acquired samples in a sparse environment
Sonar echoes can provide more than only range information, but recording the full sonar echo is challenging in resource constrained systems. This paper introduces an approach for reconstructing under-sampled sonar echo signals in environments that are not cluttered using Compressive Sensing. This technique requires sampling only around 20% of the total samples in order to achieve good reconstruction results. An experimental validation of the approach is presented.
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- PAR ID:
- 10122843
- Date Published:
- Journal Name:
- IFAC proceedings series
- Volume:
- 52
- Issue:
- 8
- ISSN:
- 0742-5953
- Page Range / eLocation ID:
- 381-386
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.101.j.ifacol.2019.08.105
