An Electromagnetic Monochord for the Measurement of Audio Frequencies

The desirable properties for an instrument for measuring frequencies over the audible range are briefly mentioned and a suggested electrically excited monochord is considered. In practice certain difficulties are found and lead to a proposal for employing the harmonic modes of vibration of the stretched wire. The theory of this is given, as well as the relation between the frequency response and the position of a movable bridge. The constructional details and the method of calibration from a single tuning fork are described in turn. Miscellaneous considerations concerning the practical operation conclude the paper.