show octave on note (guitar & piano)

[sugizo]

Description
better to show octave on note useful when play in choir
e.g. in standard choir usually use SATB (Sopran Alto Tenor Bass) which every vocal characteristic (male/female) has it's own range (base on octave)

Implementation
perhaps use button to show octave info for show or hidden the info (recommended because not every musicians care about octave can hide it, but for the detail musicians that must play within choir can show the octave)
or
simply put octave info without option to show or hide octave info

Examples
which fretboard must be press to play melody with tenor vocal on major third tuning

ref on piano
https://en.wikipedia.org/wiki/Tenor

thanks