What is a Jews harp?
The Jew's harp is one of the oldest musical instruments known to man, depicted as far back as 300 B. C. Also known as the lemellophone or jaw harp (in England, as a trump; in France, as a guimbarde), it is played by placing the tongue or reed of the instrument in the mouth of the player and then plucked with the finger to create the sound or note.
The frame is held firmly against the performer's parted front teeth, using the jaw (thus "jaw harp") and mouth as a resonator, greatly increasing the volume of the instrument. The teeth must be parted sufficiently for the reed to vibrate freely ,and the fleshy parts of the mouth should not come into contact with the reed to prevent damping of the vibrations. The note thus produced is constant in pitch, though by changing the shape of his or her mouth and the amount of air contained in it, the performer can cause different overtones to sound and thus create melodies. The volume of the note can be varied by breathing in and out.