This type of echo involves placing a device called a transducer on your chest. The device sends special sound waves, called ultrasound, through your chest wall to your heart. The human ear can't hear ultrasound waves. As the ultrasound waves bounce off the structures of your heart, a computer in the ECHO machine converts them into pictures on a screen.
The Play Scene in Hamlet. Edwin Austin Abbey (1852-1911) In this painting, which won gold medals in three international exhibitions, Abbey depicts the play scene from Hamlet (Act III, scene ii) through the eyes of the traveling players as they perform The Murder of Gonzago..
The first play we know of that was performed at Shakespeare's famous playhouse was Julius Caesar in 1599 when a Swiss tourist Thomas Platter recorded in his diary that on September the 21st  we witnessed an excellent performance of the tragedy of the first Emperor Julius Caesar said to be performed by some 15 actors.