Introduce harmonica with 50 words.

Tracing back to its source, the harmonica is actually a tuning tool. Suitable for small wind instruments. The piano body is rectangular, with different sizes and shapes. Harmonica is a multi-reed musical instrument, which makes the metal reed vibrate and sound by blowing or inhaling through the mouth; In the classification of musical instruments, it belongs to wind instruments with free springs. The sound source is a reed with a length of 1.5 ~ 3.5 cm. The harmonica originated in China and was called Sheng thousands of years ago. There is a record of "harmony" in Oracle Bone Inscriptions unearthed in the market of Yin (BC 140 1 ~ BC122). "Harmony" is the predecessor of Xiao Sheng in later generations. "Er Ya Shi Le" records: "Great prosperity is the nest, and small prosperity is harmony." This musical instrument made of bamboo reeds quickly became popular in Asia and occupied an important position in traditional music. In the late18th century, Sheng was introduced to Europe and quickly became popular in the music industry. Around 1820, a young musician named Christian Friedrich Buschmann made the first harmonica (then called Aura) with a metal reed. This aura is widely praised by musicians for its unique charm; But at that time Aura only blew the sound, but didn't absorb it. About 1825, richter, a European, invented a musical instrument, which became the prototype of modern harmonica.