\So*nom"e*ter\, n. [L. sonus a sound + -meter.]
1. (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. An instrument for testing the hearing capacity.