An instrumentation system for automatically monitoring and recording sound levels in industrial arts laboratories

Abstract

The problem of the study was to fabricate and test the sensitivity and repeatability of a sound monitoring system through the use of variable noise levels produced by a variety of machines. Specifically, the objective of the study was to design and fabricate . a sound monitoring system capable of sensing and recording for computer processing of data, multi-locational sound levels over extended periods of time. In regard to the objective the following questions were presented. (1) Is the sound monitoring system responsive to locational changes of variable noise levels emanating from identified sources? (2) Is the sound monitoring system capable of providing repeated recordings of sound levels within acceptable tolerances? (3) Is the system adaptable for detecting and recording noise levels in typical industrial arts laboratories? The instrumentation system consisted of an approved type 2 sound level meter (SLM) which was used in conjunction with a 16 microphone ma­ trix. An electronic switcher-converter was fabricated to serially switch each microphone of the matrix at precise timed intervals with each matrix cycle being registered by a digital counter. The linear voltage output of the SLM was converted to digital form and recorded on punched tape for com­ puter processing. A punch tape unit designed for the system was used to perform the recording function. The instrumentation system was tested in the wood laboratory of the Industrial Education Department at Iowa State University, where the micro­ phones were arranged in a four by four matrix spaced at 10 foot intervals.