Phonoscope \Pho"no*scope\, n. [Phono- + -scope.] (Physics)
(a) An instrument for observing or exhibiting the motions or
properties of sounding bodies; especially, an apparatus
invented by K["o]nig for testing the quality of musical
strings.
(b) An instrument for producing luminous figures by the
vibrations of sounding bodies.
[1913 Webster]