0 not able to send back an echo (= a sound that reflects off a surface):
The anechoic chamber is used to test microphone performance.
The ultrasound showed an anechoic mass located behind a normal bladder.
Those are lightweight building blocks made of some porous, anechoic material.
Experiments in anechoic chambers have shown errors of more than two to one when subjects were asked to estimate the distance of a sound source.
To overcome these problems it was decided to record heart valve sounds under controlled conditions deep in an anechoic water tank, free from reverberation noise.
In this study, 4 patients had an abnormal anechoic mass, 1 had an abnormal echogenic mass.
The case presented in ultrasound studies as a large, solid, well-defined, heterogenous mass with anechoic areas.
12.5% of the nodes were anechoic.
