I think that will be handled by the AC to DC conversion in most systems.
Nope. Mains hum is picked up by microphones as well as light intensity:
https://en.wikipedia.org/wiki/Electrical_network_frequency_a...
Nope. Mains hum is picked up by microphones as well as light intensity:
https://en.wikipedia.org/wiki/Electrical_network_frequency_a...