The answer to 'smoke detector buzzing noise' is that a smoke detector that is making a constant or intermittent buzzing, chirping, or beeping sound is typically indicating a problem that needs to be addressed. The most common causes are a low battery, a malfunctioning sensor, or the smoke detector reaching the end of its lifespan.
If the smoke detector is making a regular beeping sound, this is usually a sign that the battery needs to be replaced. Many smoke detectors have a built-in low battery warning that will sound off when the battery is getting low. Replacing the battery should resolve the buzzing noise in this case.