Modern music uses seven English letters C, D, E, F, G, A and B (or their lowercase letters) to mark the names of sounds.
The pitch distance between these seven different high-pitched and low-pitched adjacent sounds can be divided into semitone and whole tone, in which the relationship between E and F, B and C is semitone, and the relationship between other adjacent sounds is whole tone.
The pitch of the scale in each cycle is different, that is, although the sound name (or volume name) is the same, the pitch is different. When phonetic names are marked, uppercase and lowercase letters are used, or subscripts and lowercase letters are added after them to distinguish them, that is, phonetic groups.
Such as: c, B2, a, a 1 (the following number "1" should be in superscript form), B2 (the number "2" should be in subscript form). The relationship between two adjacent sounds with the same name is called "octave".
Extended data
When the seven basic tones of C, D, E, F, G, A and B change by a semitone, if they are higher than the original, they are indicated by a sharp sign (#); A semitone lower than the original sound, represented by a flat semitone (or flat semitone) (ь); The two rising semitones are indicated by double-pointed signs (×); The drops of two semitones are indicated by the double drop sign (ьь).
In the staff, the phonetic symbols written after clef to indicate the tone range used in music are called key signature. In modern European music theory, key signature is used to express tonality, because the European concept of tonality is often grasped through the expression on keyboard and staff.
In the same natural seven-tone scale, when players choose different laws from the twelve laws to form different ranges, they show different key selection methods on the keyboard.
Major:
There are seven tones in each major, and the Roman numerals you see are the series of numbers that we arrange for these seven tones. The first tone is Grade I, usually called "tonic", which is the most important tone in the whole major, and the seventh tone is Grade VII, usually called "leading tone".
Baidu Encyclopedia-Sound Name