intonator
(ˈɪntəʊneɪtə(r))
[agent-n. in L. form from intonāre to intone.]
A monochord for the study of musical intervals, furnished with a diagram indicating the divisions of the string necessary for the production of the notes of the scale in exact intonation.
| 1875 Stainer & Barrett Dict. Mus. Terms. Intonator, a monochord, or single string stretched across a flat soundboard. |