The frame is held firmly against the performer's parted teeth or lips (depending on the type), using the mouth (plus the throat and lungs when breathing freely) as a resonator, greatly increasing the volume of the instrument.

The note or tone thus produced is constant in pitch, though by changing the shape of the mouth, and the amount of air contained in it (and in some traditions closing the glottis), the performer can cause different overtones to sound and thus create melodies.

According to the Encyclopædia Britannica Eleventh Edition, "The vibrations of the steel tongue produce a compound sound composed of a fundamental and its harmonics.

By using the cavity of the mouth as a resonator, each harmonic in succession can be isolated and reinforced, giving the instrument the compass shown."

The player on the Jew's harp, in order to isolate the harmonics, frames his mouth as though intending to pronounce the various vowels.

[5] Archaeological finds of surviving examples in Europe have been claimed to be almost as old, but those dates have been challenged both on the grounds of excavation techniques, and the lack of contemporary writing or pictures mentioning the instrument.

[7] In Sicilian it is translated as marranzanu or mariolu; both of which are derogatory terms for Jewish people also found in Italian[8] and Spanish.

English etymologist Hensleigh Wedgwood wrote in 1855 that the derivation from jeu harpe opposes the French idiom, where "if two substantives are joined together, the qualifying noun is invariably the last".

"[16] Although the OED states that "the association of the instrument with Jewish people occurs, so far as is known, only in English",[15] the term jødeharpe is also used in Danish.

The brass is heated to a molten state and then poured or forced into the mold, where it cools and solidifies into the desired shape.

[23] The Jew's harp was banned in the USSR during the regime of Joseph Stalin due to its closeness to Shamanism.

[25] It is very similar to an Indian morsing or morchang in that the tongue (or twanger) extends beyond the frame, thus giving the instrument more sustain.

[37] The Austrian composer Johann Albrechtsberger—chiefly known today as a teacher of Beethoven—wrote seven concerti for Jew's harp, mandora, and orchestra between 1769 and 1771.

Thus, for example, Johann Heinrich Scheibler was able to mount up to ten mouth harps on a support disc.

Each mouth harp was tuned to different basic tones, which made even chromatic sequences possible.Well known performer Franz Koch (1761–1831), discovered by Frederick the Great, could play two Jew's harps at once, while the also well known performer Karl Eulenstein (1802–1890) "invented a system of playing four at once, connecting them by silken strings in such a way that he could clasp all four with the lips, and strike all the four springs at the same time".

[41] The American composer Charles Ives wrote a part for Jew's harp in the Washington's Birthday movement of A Symphony: New England Holidays.