DIAGNOSIS That's the bake or broil relay on the main control board chattering or buzzing. It's the switch that turns the heating element on and off, and it can get weak or dirty.
FIX Unfortunately, there's no user fix for this. The relay is soldered onto the main control board. You can try resetting the range at the breaker, but the buzzing usually comes back. The long-term fix is replacing the main control board.
IF THAT DIDN'T WORK If replacing the main board doesn't stop the noise (rare), the issue could be the bake or broil element itself arcing slightly where it connects, but that's less common than the relay.
HEADS UP While annoying, a buzzing relay often means the board is on its way out. It's still working, but keep an ear on it. If the buzzing stops AND the oven stops heating, the relay has failed completely.