What is a harmonica?

Harmonica, also known as Harmonica (English: Harmonica), is a multi-reed instrument, which makes metal reeds vibrate and sound by blowing or inhaling through the mouth; In the classification of musical instruments, it belongs to wind instruments with free springs. Because the sound source is a reed with a length of 1.5 ~ 3.5 cm instead of an air column (such as a flute), the volume of a solo harmonica is mostly 20cm×6cm×4cm (length; Wide; High), its range is slightly different according to the type and tonality. Because the relative position of reeds on the same harmonica cannot be adjusted during playing, the ability of a single harmonica to play chorus is limited.