As we know, a set of 12 keys (7W + 5B) repeats on an instrument.
This repeating set is called an Octave.
Considering a standard 5-octave keyboard,
every note appears 5 times on the keyboard.
To uniquely identify and write each note, let us first give unique names to the octaves as seen from the below diagram.
A standard 5-octave keyboard
So from the above diagram, we see that the different octaves are represented with the help of dots above or below the reference note.
But can we simply number the octaves?
Can we name the notes as C1, C2, C3, C4 and C5?
Note that many instruments having different number of octaves. Few Examples:
- Harmonium – 3.5 octaves
- Guitar – 4 octaves
- Standard Keyboard – 5 octaves
- Piano – 7.5 octaves (highest among all) !!!
Hence, considering piano as the reference, the notes are numbered according to the octaves.
So, the answer is YES.
And C4 is considered as the middle octave across all instruments.
