Ultrasound

What is Ultrasound? Sound is made up of several different frequency waves. The very high frequency range is inaudible to the human ear and is known as ultrasound. Ultrasound was used by the Navy during World War II to detect submarines, and is widely used by fisherman to help find schools of fish.

In each case, an ultrasound machine is used. With the help of a microphone-shaped device (known as a transducer) ultrasound waves are created and beamed through water. When the beam encounters a boundary or interface between liquid (water) and a solid (submarine or fish) with a different density or compactness, part of the beam is reflected back to the transducer. The remaining waves move through the object and reach the back boundary between solid and water. Here, some more of the ultrasound waves are reflected back to the transducer. In other words, the transducer transmits ultrasound and constantly receives waves that are reflected back every time the beam travels from one density to another.

The reflected ultrasound waves are collected and analyzed by the machine. Knowing the amount of time it took for the beam to travel from and to the transducer, the ultrasound machine can determine the shape, size, density and movement of all objects that lay in the path of the ultrasound beam. The information is presented on a monitor screen and can also be printed on paper. That is how ships detected submarines during World War II, fishermen identify choice fishing spots, an obstetrician can evaluate the fetus of a pregnant woman, and a cardiologist can examine the heart of a patient. There is no radiation!