The answer to 'why is my light fixture buzzing noise' is that a buzzing or humming sound coming from a light fixture is usually caused by an electrical issue. This can be due to a problem with the light bulb, the fixture's wiring, or the light switch or dimmer controlling the fixture.
Common causes include a loose or damaged light bulb, a failing electrical component in the fixture, or interference from nearby electrical devices. The buzzing noise may also be caused by a problem with the home's electrical wiring or a faulty light switch or dimmer. If the buzzing is accompanied by flickering or inconsistent lighting, it's likely an electrical issue that needs to be addressed.