Acoumeter, Politzer's. An inexpensive instrument for producing a constant sound.
Source
Stoelting, C. H. 1931. Tests for Color Perception, Visual and Auditory Acuity: Used in Railway, Miltary and Marine Services, also in the Arts and Sciences, for Research, Experimentation, Educational and Vocational Guidance. Chicago: C. H. Stoelting Co. (Collection Rand B. Evans)
