sonometer

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. See audiometer.

Century Dictionary and Cyclopedia

1. n. An apparatus used in experimenting upon musical strings or wires, and in illustrating the laws which govern their transverse vibrations. It consists of a sounding-board upon suitable supports, so arranged that two strings may be stretched above it side by side; their tension and their lengths may be varied at will by changing the position of the bridges; the strings are usually set in vibration by a bow. With this apparatus it may be proved experimentally that the number of vibrations in the musical note given by a string varies inversely as its length and diameter, directly as the square root of the tension, and inversely as the square root of its density.
2. n. An instrument, consisting of a small bell fixed on a table, for testing the effects of treatment for deafness.
3. n. In electricity, an apparatus for testing metals by means of an induction-coil, with which is associated a telephone. See induction-balance.

Wiktionary

1. n. An audiometer.

GNU Webster's 1913

1. n. (Physiol.) An instrument for exhibiting the transverse vibrations of cords, and ascertaining the relations between musical notes. It consists of a cord stretched by weight along a box, and divided into different lengths at pleasure by a bridge, the place of which is determined by a scale on the face of the box.
2. n. An instrument for testing the hearing capacity.

WordNet 3.0

1. n. an instrument used to measure the sensitivity of hearing