Overblowing

Overblowing is a harmonica technique that raises a reed above its normal pitch by changing airflow and embouchure, allowing notes outside the instrument’s ordinary diatonic scale.

Harmonica: A free-reed instrument in which breath through holes sets metal reeds vibrating. Overblowing is a way of extending the pitches available on this instrument.
Bending (harmonica technique): A harmonica technique that lowers a note by changing airflow and vocal-tract resonance. Bending usually lowers a reed’s pitch, whereas overblowing produces a higher pitch.
Chromatic scale: A musical scale containing all twelve pitch classes within an octave. Overblown notes can supply pitches missing from a diatonic harmonica’s ordinary scale.
Overblow: A high-register articulation in some wind instruments, produced by changing airflow to favor an upper register. The shared name can describe a broader wind-instrument technique, not specifically harmonica reed raising.
Free reed: A reed that vibrates through an opening in a frame, alternating airflow through and around the reed. Its vibration is the physical source of harmonica notes, including overblown ones.
Overdrawing: A harmonica technique that raises a reed above its normal pitch while drawing air through the instrument. It is the draw-breath counterpart to overblowing’s blow-breath technique.
Harmonica technique: The set of playing methods used to control a harmonica’s pitch, tone, articulation, and phrasing. Overblowing is one specialized method within this broader practice.
Tongue blocking: A harmonica playing method in which the tongue covers selected holes while the mouth spans several holes. It changes which holes sound, rather than raising a reed above its normal pitch.
Embouchure: The shaping and positioning of the mouth used to control airflow into a wind instrument. Small changes in mouth shape help select and sustain an overblown note.
Blow note: A pitch produced by exhaling through a harmonica hole and setting its blow reed vibrating. Overblowing a hole raises the pitch associated with its blow reed.

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