Why does the bus make a siren when it dings sometimes?

Question

When you ding the bell on the First buses (in Leeds at least) sometimes it makes a siren noise....whyyyyyyyyyyyyy?

Answer 1

this will always be a mystery. i hope some1 out there knows or i may end up killing myself. (simon is g*y)

Answer 2

are u pressing the wheelchair button? one kind of bus i drive does that...cant remember which one... but it makes a kinda siren sound, the same sound it makes when the wheelchair ramp is being used.