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Hearing range describes the frequency range that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 15.000 to 20,000 Hz, although there is considerable variation between individuals, especially at high frequencies, and a gradual loss of sensitivity to higher frequencies ...
Strain rate is the rate of deformation, and is negative during systole, when the ventricle shortens. Strain rate, however, becomes positive when the ventricle lengthens. Thus the more rapid phase shifts show details of the lengthening, displaying that it is not homogeneous. Strain rate colour curved anatomical M-mode. The yellow line is drawn ...
This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic waves apply to any frequency range, including ultrasound. Ultrasonic devices operate with frequencies from 20 kHz up to several gigahertz. Ultrasound is used in many different fields.
Speckle tracking is one of two methods for Strain rate imaging, the other being Tissue Doppler. Twist or torsional deformation define the base-to-apex gradient and is the result of myocardial shearing in the circumferential-longitudinal planes such that, when viewed from the apex, the base rotates in a counterclockwise direction.
The word "dopplergraph" is a combination of the words doppler and photograph. Dopplergraphs are two-dimensional records of variations in the doppler shift in light intensity. Dopplergraphs do not need to be a record of the shift of visible light, but of any radiated wave, which includes electromagnetic waves and acoustic waves. [1]
The advantage of combining Doppler processing with pulse radars is to provide accurate velocity information. This velocity is called range-rate. It describes the rate that a target moves toward or away from the radar. A target with no range-rate reflects a frequency near the transmitter frequency and cannot be detected.
Absence of the portal system in a first trimester case associated with hygroma and aorto-umbilical fistula. (A): Transverse plane of the upper abdomen with color Doppler applied, showing umbilical cord insertion, stomach, the prominent hepatic artery and no afferent liver venous perfusion; (B): midsagittal plane reconstructed from a three-dimensional volume acquisition were the crown-rump ...
For example, the speed of sound in water is 1,497 m/s, and the human body is about 0.5 m thick, so the PRF for ultrasound images of the human body should be less than about 2 kHz (1,497/0.5). As another example, ocean depth is approximately 2 km, so sound takes over a second to return from the sea floor.