The invention of the law of twelve averages brought about the establishment of chromatic scales. A chromatic scale divides an octave into twelve identical semitones or semitones, each of which is equivalent to a guitar. The ratio between every two tones is 1.059. A whole note is two semitones, which is the distance between two notes. The chromatic scale is very important, and all the other scales we use are developed from chromatic scales. With the law of twelve averages, musicians can not only make strings, but also play any of the twelve keys without the trouble of tone sandhi. Tone selection is to select the first whole tone from twelve semitones within an octave, and then construct a set of scales according to the given interval mode, and use the above method to divide whole tones and semitones. 1722, Bach showed that the application of the twelve average laws is omnipotent in his collection of piano music with average laws. One by one, this novel takes one of the twelve semitones as a faithful tone until all possible tones are used.

"Now, let's sit down and have a good look, son. First of all, we know that there are octaves in human hearing. Then, we divide an octave into twelve equal parts called semitones, and the two semitones are combined into a whole sound. Starting from the diatonic scale, the major scale of any key has the following interval arrangement.

"The setting of the piano keyboard is that if you play the scale in C major, you only need to use the white key. Moreover, the key C is also the basis of the seven tuning levels named after letters. One wonder is why they don't name it after the letter A. They didn't do that anyway. So, the result you get can be represented by the following figure:

Everything was based on 440 A notes. Using the average law, we can find the C sound below this A sound, which is called the central C, that is, starting from this C sound in the central position, we name the heart-shaped letters in turn, and each white key is named as one between the letter A and the letter G. As we all know, and as you can see from the keyboard, the major scale is not an equidistant ladder. So in order to make up for this shortcoming, there are many black keys cars on the piano, and there are five black keys in eight octaves, which are used to play the transitional semitones between the five diatonic scales. The result of this is that the E key and the F key, and the B key and the C key are directly pressed together. Now let's broaden our horizons and look at all the octaves on the piano.

The most common music notation system is the alphabetic note system, which is based on the key of C. The notation of staff is based on the key C, and a series of major scales are represented by each line or between two lines. These notes can be changed by semitones by adding a rising or falling semitone to the lines or spaces of the notes to be changed. This is the way to record works in other keys in music, that is, without using major scales. The following are two most commonly used charts, which indicate all the scales in C. The central C was originally the central boundary that we used to divide the high-pitched part and the low-pitched part, but here it falls on the lower plus line of the high-pitched spectrum. When we play the piano, the notes of treble clef are usually played with the right hand; People who use bass clef play with their left hand.

The old man took a key out of his pocket and walked to the front door of the house. He opened the door and went in. The boy followed him curiously. "Old man, you must have a lot of guitars here," the boy said, staring at the room with wide eyes.

"What can I say, son? I can only tell you that the piano and speakers are in the other room. "

There are all kinds of imaginable musical instruments and their accessories everywhere in the room from top to bottom, on the walls and on the floor. At this time, the boy couldn't help being curious about the old man. What's going on here? How can an old man who lives by the railway track have such a room full of collections? "This place is like a musical instrument store, old man."

Hearing this, the old man smiled and said, "Son, this is a music room. Just use your terminology. Now, don't be intimidated by these rich kinds of musical instruments. Remember, it is difficult to play all these instruments without hard work. Don't think about whether I'm rich or poor, son. All you have to do is sit in the chair for a while, listen to me play the blues and think about our living space. "

The old man sat down diagonally across the corner and immediately played an old and slow blues. As if this melody had been going on, the old man played as accurately as tuning the radio. The boy fell asleep slowly.