Projector Noise Levels

Analytical and empirical tests have been made to determine optimum noise levels of photographic projectors. It is shown that to achieve 96% “intelligibility” (per cent of sentences understood) the projector should have an articulation index (a quantity related complexly to noise and frequency) greater than 0.4. The index is simple to determine when the projector noise spectrum parallels the spectrum for ordinary speech, i.e., when it peaks near 500 cycles/sec. Measurement of the index is more difficult when the spectra are nonparallel.

Print ISSN

0361-4573

Published

1959-06

Content type

Original Research

DOI

10.5594/J13833