The horizontal line under the notation number is a mark indicating the length of the sound (the duration of the sound). In notation, the length (duration) of a note is indicated by adding a short horizontal line behind or below the note. The line added below the notes is called the time-lapse line, and the duration is reduced by half for each additional time-lapse line.

apart from the high and low notes in music, the notes should be expressed as long and short. Here is a basic musical term-beat. Beat is an important concept to express the length of notes. To express the length of music requires a relatively fixed concept of time. In the notation, notes are divided into whole notes, binary notes, quarter notes, sixteenth notes and thirty-second notes.

Extended data:

The simple notation uses seven Arabic numerals and dots attached above or below the numerals to indicate the sound level. Gong-chi notation is to indicate the length of the sound with the board-eye symbol attached to the right of the word, while simple notation is to indicate the length of the sound with the short horizontal line attached to the right or below the Arabic numeral. Simple notation is so close to I-scale notation, and the method of recording the pitch of sound by simple notation is simpler and more accurate than I-scale notation, so people in China are very easy to accept simple notation.

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