If a song is in A, you’ll have lots of 440Hz, 220Hz, 110Hz, 880Hz, and so on — but so what? What are you supposed to do with that information? And what about all the harmonics? And all the other notes in the key of A, and all their harmonics?
Paloma Faith’s new song ‘Only Love Can Hurt Like This’ has been recorded out of tune by about 50 cents. This means that unless you have a keyboard that can be detuned, you cannot play along! What would be the reason for doing this?