According to the purpose, harmonica can be roughly divided into two categories: solo harmonica and ensemble harmonica. The former mainly includes polyphonic harmonica (including stress and echo harmonica), semitone harmonica and blues harmonica. The latter includes bass harmonica, chord harmonica, brass harmonica and so on.

According to the pronunciation mode, it can be divided into single-spring pronunciation and multi-spring pronunciation. The chromatic and blues harmonicas belong to single-reed pronunciation, as do children's toy harmonicas, necklaces and key-chain harmonicas. Polyphony, chord and bass harmonica belong to the latter.

1. polyphonic harmonica.

This is the most popular harmonica in China and even in Asia. Generally speaking, polyphonic harmonica has 16 to 28 holes, of which 24 holes are the most common variety in China. Japanese polyphonic piano also has 2 1 hole. The holes of the polyphonic piano are divided into two rows. Generally, when playing, the upper and lower reeds of the same hole sound at the same time. Because the vibration frequencies of the two reeds are slightly different, at the same time, the vibration will produce a phenomenon called "beat" in physics, which is characterized by periodic changes in sound intensity, also known as "vibration". This is why the polyphonic harmonica is called "polyphonic" abroad. Stress harmonica and echo harmonica can be considered as variants of polyphonic harmonica, both of which belong to polyphonic category. The former has an octave relationship between the upper and lower reeds, and the timbre is full and round; The latter has a cylindrical piano cover (piano shell) and has a unique * * * effect. The polyphonic harmonica has no less than 12 keys, the most common key is C, and there are also many A keys. The piano with C key has a high range, which sometimes seems harsh. It is generally believed that the range of piano is closest to human voice. In addition, a harmonica has two tones at the same time and a chromatic difference, so it can play chromatic scales and realize tuning. Not much to say, please consult the relevant information.

2. chromatic harmonica.

Chromatic harmonica is a more serious instrument than polyphonic harmonica. A complete chromatic scale, with a maximum range of more than four octaves, makes chromatic harmonica, who was born not long ago, occupy a place in regular musical instruments. Although not a full member of the traditional symphony orchestra, with the efforts of many harmonica masters, chromatic harmonica has gained a certain position in the field of chamber music, and there are also orchestras with chords and bass harmonicas at home and abroad. The common chromatic harmonica is that there are four sounds in a hole, and the sound absorption becomes a two-dimensional relationship. When the tone change key is pressed, each tone is raised by a semitone. As for the number of holes, there are 8, 10, 12, 14, 16 and so on. The range is two to four octaves, mostly in C. This kind of harmonica is suitable for playing more complicated music because it can play all semitones in the range. Chromatic harmonica's learning threshold is higher than polyphonic piano. On the one hand, it is difficult in music theory, on the other hand, it is also difficult to play: playing chromatic scales requires much higher breath control than polyphonic pianos, and at the same time requires strict coordination among breath, piano keys and keys. In addition, due to the production process, cost and other reasons, there are also manufacturers producing chromatic harmonica with one hole and two tones. Common ones are domestic 24-hole 48-tone piano, Japanese 17-hole piano and 22-hole piano. There is also a unique chromatic harmonica, which is similar to a polyphonic piano. It has two rows of holes, and the upper row is half a tone higher than the lower row. It is generally considered that the design of one hole and four tones is more formal. As far as I know, there is no precedent for famous artists to choose the latter two kinds of pianos.