Tuning a guitar (or other stringed instrument) so that the strings are more or less in tune with each other is a really basic skill that even very amateur players can mostly do. Being able to tune to an absolute pitch without any kind of reference is kind of freakishly rare.
Re:Google adds a guitar tuner to Search
by TedDoesntTalk on Monday October 11, 2021 @07:44AM
(#28827247)
This. Use harmonics after getting the A from an external source.
Re:Google adds a guitar tuner to Search
by jm547ster on Monday October 11, 2021 @05:54AM
(#28826588)
Yeah 95% or more will need a tuning fork at a minimum to give a frame of reference. It is fairly common for strings accompanied by a piano to ask for a note from the piano to start from (G for violin say)
In the case of ensembles with a piano, I've heard it's because you can't retune the piano in the minutes before the performance. So it makes no sense for musicians to tune to a fork (or using an electric tuner) and leave the piano out of tune, so they all take the key tone from the piano
Pianos need regular tuning too, done by experts - they change tone depending on weather, temperature and humidity as well, so they have to be in a stable environment if at all possible. But these people can mostly tune them by ear, or they will have a tune fork for the base tone (A I believe) and work from there.