NEMA MG 3:1974 (R2014)

FOREWARD In recent years noise has had an increasing influence on users of machines. Exposure to excessive noise levels may cause permanent hearing damage and, also, affect people's efficiency, moods, temperament and comfort. Local, State and Federal Governments have enacted legislation to control noise level exposure. Due to the recent emphasis on health and safety considerations, a large number of people with no special training in sound have had noise control problems thrust upon them. This booklet provides a method of predicting approximate sound pressure levels in industrial and commercial areas. The method is intended for estimating sound pressure levels and should not be construed as a guarantee of results. It requires a knowledge of the sound levels, location of all sound sources, and room characteristics. Throughout this booklet, for simplicity, emphasis is placed on the use of overaldl BA . A more detailed analysis can be obtained by using the same method for each octave band sound level as shown in the Appendix. Machine sound level data are normally expressed as singled dBA levels or in full octave bandd dB levels, unweighted, in terms of sound pressure or sound power.*An example is included to assist the reader in understanding the method described in the publication. Instructions for calculation are followed immediately by corresponding sample calculations for convenient reference.