Harmonicas

A harmonica, also known as a mouth organ, is a small free-reed instrument held to the mouth and played by blowing or drawing air through its holes. Inside a harmonica, thin metal reeds vibrate as air passes over them, producing musical notes. The reeds are mounted in reed plates and housed in a comb, which can be made of plastic, wood, or metal.

Harmonicas come in several main types. Diatonic harmonicas typically have 10 holes and are designed for playing in a given key, producing a major scale with basic blues and folk sounds. Chromatic harmonicas usually have 12 holes and a button-activated mechanism that directs air to produce all semitones, enabling chromatic playing. Tremolo harmonicas use pairs of reeds tuned slightly apart to create a shimmering, warbling effect. Octave harmonicas duplicate notes at the octave or more to extend range. Larger models include bass and chord harmonicas, which provide accompaniment with multiple reeds.

The modern harmonica originated in the early 19th century in Europe, with development by various makers in Germany. Matthias Hohner popularized the instrument internationally in the 19th century, and the name harmonica derives from a Greek term related to harmony. Since then, harmonicas have been produced by many manufacturers and used across diverse musical genres.

Playing technique centers on directing the player's breath into or out of the holes while shaping the mouth and tongue to control tone and pitch. Players can bend notes on many diatonic models to obtain pitches outside the standard scale, and advanced techniques such as overblows extend the instrument’s range. Harmonica playing is prominent in blues, folk, jazz, and world music traditions, with notable performers including Little Walter, Sonny Boy Williamson II, and Toots Thielemans.