signal instrument
musical instrument which is not only used for music as such, but also fit to give sound signals as a form of auditive communication, usually in the open air
door knocker
item of door furniture
hunting horn
type of horn instrument used by hunters for signalling
Acme siren
musical instrument that sounds like police siren
post horn
brass instrument
signalling whistle
any type of whistle or flute used for signalling
bugle
type of brass instrument
pea whistle
small whistle which produces a trill sound as air passes over a small ball or dowel rod placed inside it