Reverberations are formed when a sound wave bounces between 2 strong specular reflectors (the reflectors are at 90 degrees to the ultrasound beam). These strong reflectors cause the ultrasound beam to bounce back and forth between them. Once this reverberated ultrasound beam comes back to the machine, it interprets an image as if it is from deeper structures since it took longer to get back to the transducer. The echoes that appear at increasing depths do not correspond to any anatomic structure. Think of the ultrasound beam as being partially trapped in between them and only returning at a later time. The result is of equally spaced images beyond the actual structure of interest.
To eliminate this effect attempt tilting the transducer so that the reflective surface is no longer at 90 degrees to the ultrasound beam by altering the angle of incidence between the beam and the structure.
Examples of reverberation artifacts seen while examining the lung. 1, the display shows multiple, equally spaced echoes creating equally spaced hyperechoic A-lines representing reverberations of the pleural line. Blue arrows denote the direction of the ultrasound beam. Notice that in i the beam reflects back but is trapped by the pleural line in ii, causing a delay of the return of signal to the probe; 2, Comet-tail artifacts forming B lines that originate from the pleural line and appear hyperechoic that extend indefinitely erasing A-lines and moving in concert with lung sliding.