Pitch bending in the diatonic harmonica

Pitch bending by wind instrument players is standard practice in many genres of music, but it is considered essential in blues harmonica playing. Some simple pitch bends involve the coupling of a single reed to a resonator such as the vocal tract of the player, but a full description of pitch bending in the harmonica involves consideration of the coupling between the two reeds, one for each direction of airflow, that share a single reed chamber. The most common pitch bends are those for which the primary reed in the reed chamber sounds a note higher in frequency than that sounded by the secondary reed. In these cases notes can be bent downward to pitches between those sounded by the two reeds. In addition, some players use more advanced techniques to bend notes beyond the frequencies of the chamber reeds. This paper reviews experimental work and theoretical modeling done on pitch bending in the harmonica during the last thirty years. This includes measurements made while pitch bends are produced by players as well as experiments on harmonicas in more conventional laboratory settings.