acoustic shadow

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a·cous·tic shad·ow

sonographic appearance of reduced echo amplitude from regions lying beyond an attenuating object. Compare: acoustic enhancement.

acoustic shadow

in an ultrasound image, the absence of echoes produced by the presence of dense material, such as calculi, which impede the transmission of sound waves. It is often used to detect biliary calculi.
References in periodicals archive ?
It also includes aspects of technology, culture, and physical phenomena that influenced the outcomes or documentation of the war, such as the early ambrotype photograph, influential newspapers, the practice on conscription, and the phenomenon of acoustic shadow.
Additionally, as male breast cancer typically occurs in an eccentric subareolar location, sonographic localization and evaluation of lesions can be complicated by the dense acoustic shadow of the nipple.
Barriers protect the receiver from direct airborne sound waves by reducing the noise level in the acoustic shadow zone.
It can be hypothesized that the explosive wave of compression and rarefaction resulted in the rupture of the small blood vessels on the side facing the blast, but those on the other side were protected by the acoustic shadow of the skull.

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