I can think of a number of possibilities.
Faulty electrical wiring.
Insects/pests/animals.
wind (causing a loose item to vibrate)
Air conditioning (see above)
Central heating (water) pump noise.
Tinnitus.
Where is the noise coming from? Under then hood, or interior?
A loud buzzing noise coming through the speakers in a Mercedes Benz 1994 c280 could be the result of an issue with the ground. You should check that first to see if it fixes the issue.
there is a constant buzzing from fuse box until signal or hazards are activated or until turn signal fuse is pulled
engine noise coming thru the radio is caused by a bad ground somewhere so instead of chasing that you go to a car stereo shop and buy a noise filter that hooks up to the ground wire coming off the radio.
cicadas
Both bees and mosquitoes make the buzzing noises with their wings. Their wings are moving at such a high rate of speed that it makes the vibrations and buzzing sounds.
Because their wings move so fast that it creates a buzzing noise
Not knowing what this fuse box is for is hard to say. For a house, any buzzing noise is not good, this indicates a leakage of electricity which is never good. There could be a weak fuse or loose wire and this can be dangerous. Have someone look at the fusebox to be on the safe side.
Well, this is certainly among the strangest questions I've seen here. Is the buzzing from the headlight it's self, or is the noise inside the cabin?
The breaker makes a buzzing noise when turned on because of the electrical current flowing through it, causing the internal components to vibrate and produce the sound.
Your amp may be making a buzzing noise due to a grounding issue, a problem with the power supply, a faulty cable, or interference from other electronic devices.
Bees can produce buzzing sounds by the rapid movement of their wings. The buzzing noise is created when the wings beat against the air at a high frequency. Bees use this buzzing sound for communication within the hive and to signal danger or excitement.