There is an eerie bass sound coming from our flush toilet. It sounds like this.
Usually it starts when we sit on the toilet or push it, but sometimes it starts even when we are away. Each time it starts, it lasts for several seconds, then halts.
Other than this, the toilet works fine - there is no apparent water-dripping.
What should we do? Do we have to replace the entire toilet? The entire water tank? Or just some part of it?