In this paper, we consider received radar echoes data of moving ground targets and represent the corresponding signals in the time-frequency domain using spectrograms. The objective of the paper is to identify and validate the intrinsic spectrogram-based features characterizing the different classes of targets, and subsequently extract salient features for classification. We will show examples ...

In this article the author proposes an episodic theory of spoken word representation, perception, and production. By most theories, idiosyncratic aspects of speech (voice details, ambient noise, etc.) are considered noise and are filtered in perception. However, episodic theories suggest that perceptual details are stored in memory and are integral to later perception. In this research the auth...

BACKGROUND A small number of blind people are adept at echolocating silent objects simply by producing mouth clicks and listening to the returning echoes. Yet the neural architecture underlying this type of aid-free human echolocation has not been investigated. To tackle this question, we recruited echolocation experts, one early- and one late-blind, and measured functional brain activity in ea...

Big brown bats emit biosonar sounds and perceive their surroundings from the delays of echoes received by the ears. Broadcasts are frequency modulated (FM) and contain two prominent harmonics sweeping from 50 to 25 kHz (FM1) and from 100 to 50 kHz (FM2). Individual frequencies in each broadcast and each echo evoke single-spike auditory responses. Echo delay is encoded by the time elapsed betwee...

The biosonar system of dolphins and porpoises has been studied for about 5 decades and much has been learned [Au, W. W. L. (1993). The Sonar of Dolphins (Springer, New York)]. Most experiments have involved human-made targets; little is known about odontocetes' echolocation of prey. To address this issue, acoustic backscatter from Atlantic cod (Gadus morhua), gray mullet (Chelon labrosus), poll...

BACKGROUND The anatomic-electrophysiological correlation of AV nodal reentry is unclear. To localize reentrant circuits during atrial and ventricular echoes and to characterize sites of slow conduction and block, we correlated histology with electrophysiology of the AV node. METHODS AND RESULTS In 10 isolated dog hearts, extracellular electrical activity was recorded in Koch's triangle at 208...

This paper applies acoustic principles and a novel scanning method motivated by acoustic flow to recognize retro-reflectors directly from sonar echoes while performing drive-by scanning. Right-angle corners and cylinders form specular retro-reflectors that produce strong echoes whose features can be easily identified. A multi-point sonar produces a point process whose density encodes the echo a...

We present long-overdue details about the intensity and spectral characteristics of 150-km echoes observed by the São Luı́s radar in Brazil. The São Luı́s observations show that the echoes usually come from multiple scattering layers that descend in altitude before local noon, and ascend during afternoon hours, similar to what has been found in observations made in other longitude sectors. The la...

This paper considers the problem of simultaneous 2-D room shape reconstruction and self-localization without the requirement of any pre-established infrastructure. A mobile device equipped with co-located microphone and loudspeaker as well as internal motion sensors is used to emit acoustic pulses and collect echoes reflected by the walls. Using only first order echoes, room shape recovery and ...