pistonphone vs acoustic device

pistonphone and acoustic device both are nouns.

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

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

pistonphone: an acoustical calibrator (sound source) that uses a closed coupling volume to generate a precise sound pressure for the calibration of measurement microphones.
acoustic device: a device for amplifying or transmitting sound

pistonphone (noun)	acoustic device (noun)
an acoustical calibrator (sound source) that uses a closed coupling volume to generate a precise sound pressure for the calibration of measurement microphones.	a device for amplifying or transmitting sound