I've wondered about the effects of 60 cycle hum. If 440 is an A, I believe 60 is a B. In a lot of popular musical scales this is a dissonant tone. Dissonant tones are associated with anxiety. Is constant 60 cycle hum giving people anxiety?
If practicing an area with electrical hum, tuning A down to 420 (7 * 60) is definitely a relief.