What is octave?

From a scientific point of view: in music, two sounds with the same name in adjacent sound groups, including changing sound levels, are called octaves.

On the piano keyboard, starting from a key, the key separated up or down by seven white keys is an octave. As shown in the figure:

The so-called "octave" refers to two notes that are octave in interval relationship, that is, they are called "octave" each other.

The octave in the sound name and the notation notes in the digital notation all use the same name and symbol. For example, when we say "C", we include all the musical sounds called "C". There is an octave relationship between C 1 of large group, C of large group, C of small group, c 1 of small group, c2 of small group, etc.

Another example is the relationship between 1 recorded in the notation and me, which is the octave relationship.

As we all know, the pitch of music is determined by the volume of its audio. The higher the audio, the higher the pitch. Then, when the audio ratio of two tones is exactly 2, the relationship between the two tones is an octave. For example, a 1(440Hz) and a(220Hz), when the audio ratio of a 1 is 440: 220 = 2; So a 1 and a are both octaves.

Two tones in the octave relationship, because their audio is very harmonious, never interfere with each other (bass vibrates once, treble vibrates twice). Therefore, in the nature of sound, the two tend to be completely consistent, with only the difference in pitch and no essential contrast. Therefore, they are considered to be sounds of the same nature and adopt the same sound name.

In the position of scale, octave is the eighth in the scale, so it is called "octave". For example, C natural major scale: c d e f g a b c 1, where c 1 is the octave of C.

Therefore, in music, any tone with two identical letters is an octave.