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Dosimetry
Range of sound
053-669, Rev A eg5
3
Range of sound
Sound pressure is measured in decibels, or tenths of a Bel. Sound
pressure level is indicated as dB SPL. Since the human ear can detect
sounds with an extensive range of amplitude, a decibel scale is used to
simplify the measurement results. For example, the ratio between the
threshold of hearing and threshold of pain in the human ear if
measured in true energy is 10,000,000 times! The same range using
the dB scale is 0 - 140 dB referenced to 20 µPa (Micropascals).
The quietest sound that humans can hear has an amplitude of
approximately 0 dB. Prolonged exposure to sound pressure levels
exceeding 85 dB can cause permanent damage to the ear. Sound
levels in excess of 130 dB are more than the human ear can safely
withstand and can result in serious pain and permanent damage.
What do the standards say?
Many organizations have studied and analyzed the effects of high
sound exposure on hearing. As a result, standards were developed to
regulate personal noise exposure. In the United States, the
Occupational Safety and Health Administration (OSHA), the Mine and
Safety and Health Administration (MSHA), and the American
Conference of Governmental Industrial Hygienists (ACGIH) have all
created regulations and limitations on total permissible noise exposure.
International standards are specified by the health and safety
regulations such as the European Union (EU) Directive 2003/10/EC.
Additionally, the International Electrotechnical Commission (IEC) IEC-
61252 has specific guidelines and regulations to monitor noise in the
workplace.
To access these copyrighted standards, please refer to the following:
 OSHA - http://www.osha.gov
 MSHA- http://www.msha.gov
 NIOSH - http://www.cdc.gov/niosh/topics/noise
 ACGIH - http://www.cdc.gov/niosh/topics/noise
 IEC - http://www.iec.ch