Have you noticed on stage at a live performance between every number the guitarist reference some clip on their headstock or look at the floor before starting the next tune?
The fine art of Tune-Ying was not always critical for a show to stop but today it is part of the dance. Actually it is better for the audience (if they can hear over the drums and the crowd yelling) and better for the band to play the right notes.
So what is all about this Ancient Chinese Art of Tune-Ying?
I won’t get into the theory of pitch, harmonics, tones, timbres and chromatic scale but when an instrument is tuned, then when you play a ‘C’ it sounds like the ‘C’ the composer expected to hear.
You’ve heard orchestras sit down before the conductor comes out and all start playing one note. I’ve heard that note is Bb but some say it is A#. I have no clue how all these wind and brass instruments can tune for I’m a string man but they make this incredible noise before some old guy in a tux comes out and taps a stick on a podium to get them to stop.
Back in the day, as I remember, those country or folk players never checked their guitars for proper sound. They played by ear and maybe if it sounded right for them, it would sound right for the listener. A piano, if available, was used to find middle ‘C’, then a pitch pipe was used before performances, but only occasionally would a guitar picker stop and retune his/her guitar. The audience never noticed because there was a story covering the process of trying to stretch the strings to an acceptable note.
Twelve string guitars took a bit longer so open tuning was used to bypass all the effort.
Today there are these clip-on gadgets that attach to the headstock that catches the vibrations of the neck to indicate if a note if sharp or flat. Also tuning keys have become more accurate to hold a string against slippage while playing.
Like eating the right food and getting enough sleep and treating animals and children with care, staying in tune is important to make the music sound good.