User Guide

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Plantronics Acoustic Safety White Paper
Draft #4
Plantronics Acoustic Safety
White Paper
©2017 Plantronics, Inc. All rights reserved. 2.17 6826
The reference effective pressure is a threshold of hearing. It is the RMS (root mean square) sound
pressure of the lowest audible sound of a 1,000 Hz tone, at 20*10
-6
Pascal. As the equation shows,
doubling the pressure, meaning two times P, increases 6 dBSPL. Figure 1 shows the decibel levels
of some common sounds.
II. An overview of key acoustic safety regulations and
industry standards
Most countries have acoustic safety regulations that govern how much noise the workers in their
country or region can safely be exposed to. The regulations are more or less similar, but with subtle
and notable differences. As an example, below is a comparison of the US and EU regulations:
US REGULATIONS: OSHA MANDATED NOISE MAXIMUMS
The Occupational Safety and Health Administration (OSHA) regulates employers’ responsibilities to
employees. OSHA Regulations 29 CFR 1910.95, Occupational Noise Exposure require employers to
ensure that employee noise exposure does not exceed specified limits for three different noise mea-
surements. These regulations pertain to:
• Impulse noise: The highest maximum noise level permitted relates to noise of very short
duration. These noises are described in the regulations as “impact” or “impulsive” noise.
Examples include gunshots and line noises such as clicks or pops. OSHA regulations limit
impulse noise to 140 dBSPL, which can be measured with a sound meter equipped with a
peak detector.
• Continuous noise: The regulations set a lower limit for noises that last longer than impulse
noise (i.e., 500 milliseconds
2
or longer in duration) and may extend over seconds, minutes or
hours. Continuous noise must not exceed 115 dBA.
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• Time-weighted average (TWA): OSHA also requires employers to limit the average of all levels of
impulsive and continuous noise that employees are exposed to during an eight-hour workday.
– Action level is 85 dBA. When noise exposure exceeds this level, OSHA requires employers
to administer a hearing conservation program that includes annual hearing tests.
– The exposure limit is 90 dBA. Employees shall not be exposed to average noise above
this level.
40dB
Raindrops Normal
Conversation
Busy City
Traffic
Hair Dryers Rock Concert Jack Hammer Gunshot /
Firework
65dB
85dB
90dB
110dB
120dB
140dB