Title: Use of graphic level recorders as indicating instruments. II. Performance in environmental noise measurements
Abstract: In the course of investigating the ability of graphic level recorders to meet the “fast” and “slow” sound level meter characteristics (ANSI S1.4-1971), some differences were noted between the response of a level recorder and sound level meter known to fulfill the same indicating instrument specification. This occurrence may be attributed to the basic differences in operating principles of the instruments involved, and apparently can exist within the definition of the sound level meter. To obtain an estimate of the differences which may be encountered in practical environmental noise measurements, direct comparisons between a sound level meter and graphic level recorder were made for four situations: nearly constant ambient noise, construction noise, truck passbys at 50 ft, and a pile driver. These sounds were chosen to provide progressively more challenging demands on the response of the instruments to fluctuating sound levels. In each case, the sound level meter is assumed to provide the “correct” reading as it is the instrument specified for the enforcement of most environmental noise regulations.