Sorry was not more specific. The buzzing noise occurs randomly and usually when it hasn't been used for a few hours. Once you flush the toilet, the noise stops. It sounds like it might be coming from the water piping. It's a 2 yr old toilet. (We just built our house 2 years ago) It is a one piece toilet but I don't know what brand. I can look inside the tank if needed but I'm not real handy with plumbing tools. I had mentioned it to the construction guy who works for the builder and he examined it and said he didn't see any sign of water leakage or problem with the tank. The toilet in the other bathroom doesn't make this noise.