A bank alarm is a security system designed to alert people of a potential threat or danger. It is usually triggered by an intruder entering the premises, and it can be heard from a distance. The term 'bank alarm' is often used interchangeably with the term 'FOGHORN, ' which is a loud, low-pitched sound that is used to warn of danger. Foghorns are typically used in maritime settings, but they can also be used in other contexts, such as banks, to alert people of a potential threat.