sonometer

/S AO1 N AH0 M IY0 T ER0/
noun
  1. 1

    An audiometer (device for gauging the hearing).

  2. 2

    An instrument for measuring sounds or their intervals by means of a sounding board with strings stretched above it, movable bridges, and weights for varying the tension.

Source: https://en.wiktionary.org/wiki/sonometer