ABSTRACT
Ultrasound is a pressure wave with a frequency above the audible range of a human ear
(18-20 kHz); it is generated by a mechanical motion that induces the molecules in a
medium to oscillate around their rest positions. Due to the bonding between the
molecules, the disturbance is transmitted to neighboring molecules. The motion causes
compressions and rarefactions of the medium and thus a pressure wave travels with the
mechanical disturbance (Figs. 1 and 2).
