SERIES & NO. SMI SUBJECT: GUIDELINES FOR CONDUCTING ENVIRONMENTAL NOISE MEASUREMENT SURVEYS

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1 1 of 5 SUBJECT: GUIDELINES FOR CONDUCTING ENVIRONMENTAL NOISE I. PURPOSE This Instruction is issued to establish a uniform practice for conducting plant environmental noise surveys and to instruct plant personnel regarding the methods for conducting such surveys. REFERENCE Plant Engineering & Environmental Planning Office Procedure No Federal and State Occupational Safety & Health Acts Chrysler Sound Level Specifications for Industrial Machinery and Equipment II. FUNCTIONS AFFECTED Manufacturing Engineering Employee Safety Industrial Hygiene III. OPERATIONS AFFECTED Chrysler Corporation IV. BACKGROUND V. GENERAL Plant noise measurement surveys throughout Chrysler Corporation generally have been conducted by Personnel activities as part of the Chrysler hearing Conservation Program. However, surveys are also needed to support engineering programs involving facility environmental noise problem analysis and correction. This document has therefore been developed to establish uniform practices in sound level measuring techniques and administrative practices as a part of the Chrysler comprehensive noise abatement program. Additional information on noise measurement and control may be obtained from the Chrysler "Sound Level Specifications for Industrial Machinery and Equipment" document. This instruction is established to provide the following:

2 2 of 5 A. A method to conduct detailed noise surveys by worker station which will determine employee exposure and provide information for effecting noise control measures. B. A plant noise survey record form to promote uniform documentation of sound level data (Exhibit A). C. An administrative system of reporting and follow-up. VI. INSTRUMENTATION A. Sound pressure levels shall be measured with a general purpose sound level meter conforming to ANSI SI Type 2 or better when set for "A" weighted slow response or with an integrating sound level meter having similar accuracy. B. Impact noise shall be measured with an instrument capable of measuring Peak sound pressure level, having a peak reading mode with a rise time of 100 microseconds or less. C. Calibration of instruments shall be performed per the manufacturers' recommendations before and after a group of sound measurements. The calibration method shall include the microphone and any extension or cable between the microphone and the meter. A suitable standard sound source shall be used. Generally, calibration shall be done on the "C" weighted scale except when the sound source frequency is 1000 HZ. (All scale readings are identical with a 1000 HZ pure tone.) The time of each calibration and battery check shall be recorded on all survey forms to which they apply. When unexplained calibration adjustment or battery replacement are found necessary, all questionable data shall be repeated. VII. GENERAL SURVEYS A. General observations shall be made to identify specific suspected areas where noise level may be a problem. B. All readings shall be taken with maximum utilization of area machinery unless otherwise noted on the survey record (see Exhibit A). C. Any nonrecurring unrelated transient noise, such as a truck passing area, shall be noted and recorded with appropriate comments when taking sound readings. D. Repetitive changes in sound pressure level shall be recorded individually with respective time exposures so that combined effective exposure may be calculated per Figure 1.

3 3 of 5 E. All sound level readings shall be taken and recorded in a manner that will allow duplication of measurement conditions at a later time for accurate evaluation of factors contributing to the noise environment. VIII DETAILED SURVEYS A. Detailed noise surveys shall be performed by measuring sound pressure levels as outlined in Section VII, B through E, at worker stations with the microphone located at the employee ear position. B. Impact exposure levels shall not exceed 140 db sound pressure level as measured with an approved peak reading sound level meter. C. If a worker must move to different areas, two or more typical average sound pressure level readings shall be determined. Combined effective exposure may be calculated per Figure 1, or the highest level may be recorded. D. When an employee's work area has an exposure level above the average sound pressure level of 85 dba, the anticipated control measure shall be indicated on the survey record. E. For noise measurements on special purpose equipment refer to the Chrysler "Sound Level Specifications for Industrial Machinery and Equipment" document. IX. FOLLOW-UP OF NOISE CONTROL PROGRAM A. Results of detailed surveys in which employee average exposure is at or above 85 dba shall be recorded on area layouts. For rapid problem definition, a color coded noise map can be developed by identifying noise levels from 85 dba to 89 dba with one color and 90 dba and above with another color on a plant layout. B. Priorities on implementation of engineering controls shall be assessed based on: 1) noise level prevalent 2) number of employees affected 3) availability of a feasible solution C. Comprehensive plant summaries and the anticipated actions to be taken shall be prepared listing all work areas with sound pressure levels at variance with the Federal Regulations.

4 4 of 5 Publications of summaries shall be made yearly. D. Status reports of active noise investigation and reduction programs shall be published frequently to monitor progress. E. Information copies of all noise program status reports, yearly plant summaries, other related noise reports, and questions concerning these guidelines shall be directed to Plant Engineering and Environmental Planning, CIMS , and Manager, Industrial Hygiene, CIMS Overall knowledge of Chrysler noise problems is necessary to these departments in order to effectively make financial priority recommendations in funding OSHA programs.

5 5 of 5 Figure 1 Combined effective exposure of two or more levels is the sum of: C 1 + C C N T 1 + T 2 T N where C N is total time exposure at any level T N is allowable time at or above level Sum of fractions shall not exceed one to be in compliance. Impact exposure shall not exceed 130 db peak sound pressure to be in compliance.

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