Monthly Round Up of Important Ideas and Standards in
Industrial Hygiene and Safety
IN THIS ISSUE: Noise Testing Instruments
Hearing loss caused by the work environment is a significant issue. Where high noise levels are present, employers are obligated to determine whether employee exposures exceed occupational guidelines. Whether conducted in-house or by a trained industrial hygienist, sound level meter and noise dosimeter testing is an important part of hearing conservation. When determining an employee’s noise exposure, there are two types of noise testing instruments, sound level meters (SLM) and noise dosimeters. SLM measure instantaneous noise, and noise dosimeters average noise levels over time.
Sound Level Meters
SLM can be used to identify where employees may be exposed to high noise. Some SLM can be equipped with an octave band analyzer which breaks down noise into various frequencies and octaves.This device can pinpoint the specific part within a machine that is the source of the noise. Some machinery can be equipped with an octave band analyzer which breaks down noise into various frequencies and octaves. This tool can pinpoint the specific part within a machine that is the source of the noise.
Similar to a SLM, a noise dosimeter measures sound levels in decibels. However, the dosimeter is worn by the employee near the ear. It integrates, by averaging, noise levels in order to determine the personal noise exposure during the work-shift or sampling period. Results are expressed as a noise dose or in decibels. The noise dose is a percentage of an 8-hour work day. As per the OSHA noise standard, a 50-percent dose is the equivalent of 85 dB of employee exposure over eight hours.
There are both Type 1 and Type 2 SLM and dosimeters. Both instruments measure in decibels in either the A weighted scale (dBA) which predicts the damage risk of the ear or the C weighted scale (dBC) the was originally designed to be the best predictor of the ear’s sensitivity to tones at high noise levels. OSHA instruments measure in dBA.
- Type 1 SLM and Dosimeters are preferred for the design of noise controls and have an accuracy of ±1 dBA.
- Type 2 SLM and Dosimeters are suitable for most compliance purposes, readings with an accuracy of ±2 dBA.
Recently, smart phones have provided sound level meter apps. They can be useful screening tools, but their accuracy varies. They should not be used for compliance purposes. Both sound level meters should be checked with a calibrator before each use and calibrated annually by the manufacturer.
For more information on this topic and to discuss your company’s safety and industrial hygiene needs call OccuSafe at (214) 662-6005 or contact us at firstname.lastname@example.org Also check: www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9742.
OccuSafe Industrial Hygiene & Safety, Inc. provides skills and expertise to recognize, evaluate and control hazards and injuries in the areas of industrial hygiene, occupational safety and health. OccuSafe services companies of all sizes in a range of industries.
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