Annoyed by the persistent dripping of water in a bucket, one scientist set out to learn what creates the distinctive sound.

A dripping sink sound can be stopped by using dish soap, researchers from Cambridge, England say. They show how a tiny air bubble makes the characteristic "plink" sound.

Despite the fact that humans have been kept awake by the sound of dripping water from a leaky tap or roof for generations, the exact source of the sound has not been known until now.