ear trumpet vs acoustic device

ear trumpet and acoustic device both are nouns.

Word	Noun	Adjective	Verb	Adverb
ear trumpet	Yes	No	No	No
acoustic device	Yes	No	No	No

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

ear trumpet: a conical acoustic device formerly used to direct sound to the ear of a hearing-impaired person
acoustic device: a device for amplifying or transmitting sound

ear trumpet (noun)	acoustic device (noun)
a conical acoustic device formerly used to direct sound to the ear of a hearing-impaired person	a device for amplifying or transmitting sound