Definition Measurement Apparatus

A laboratory apparatus for the measurement of acoustic “definition” or “clearness” as proposed by Professor Erwin Meyer [J. Acoust. Soc. Am. 26, 630–636 (1954)] has been built and used to determine the definition of several school classrooms. This paper will describe the instrumentation used for making these measurements and discuss a few of the typical readings. Further results of the definition measurements will be presented in the paper “Acoustic Measurements in School Classrooms” by Mr. R. N. Lane et al.