Other forms: doorbells
A doorbell is a signal that a visitor can use to let you know they're at your door. Most doorbells have a small button that rings a bell inside the house when it's pushed.
Your doorbell might emit a long chiming ring, even playing part of a song, or it may make a harsh buzzing sound. Doorbells tend to be louder than a simple knock on the door, and often they can be heard throughout a house or apartment. The very first doorbells were developed by the Scottish inventor William Murdock in the early 19th century.