A large, barred metallic gate opened with slight keys rattling and then closed.
A school bell or fire alarm ringing from a close perspective.
A built up, suspenseful special effect siren.
A factory or industrial warning alert or alarm.
An emergency or restricted access alarm.
A mobile phone alarm or phone call ring with a bell.
A alarm beep of digital clock or a hospital machine.
A ringing train crossing alarm in the distance.
A ringing bell of a old style telephone.
A sequence of six different buzzer sounds evenly spaced.