siren vs acoustic device

siren and acoustic device both are nouns.

Word	Noun	Adjective	Verb	Adverb
siren	Yes	No	No	No
acoustic device	Yes	No	No	No

As nouns, acoustic device is a hypernym of siren; that is, acoustic device is a word with a broader meaning than siren:

siren: an acoustic device producing a loud often wailing sound as a signal or warning
acoustic device: a device for amplifying or transmitting sound

Other hypernyms of siren include alarm, alarm system, warning device.

siren (noun)	acoustic device (noun)
eellike aquatic North American salamander with small forelimbs and no hind limbs; have permanent external gills	a device for amplifying or transmitting sound
an acoustic device producing a loud often wailing sound as a signal or warning
a warning signal that is a loud wailing sound
a woman who is considered to be dangerously seductive