ANSI S12.42 / S3.19

ANSI/ASA S12.42-2010 Methods for the Measurement of Insertion Loss of Hearing Protection Devices in Continuous or Impulsive Noise Using Microphone-in-Real-Ear or Acoustic Test Fixture Procedures International.

Hearing Protection Standards

Hearing Protection Standards guide noise safety when noise cannot be sufficiently reduced due to the intrinsic properties of a particular action or environment. Tools used at, for example, construction sites, frequently cannot be made any quieter, and the worker’s proximity to the tool means the sound cannot readily be attenuated either. This leaves the utilization of hearing protection as a major component of a noise safety arsenal. Other times, people are only temporarily subjected to loud noises, making it so that the use of individual hearing protection is more effective than dealing with the noise itself. Key examples of this case are demolitions, where the noise is very loud but short lived, or rooms that are always loud but only require human presence at limited intervals.

This standard specifies microphone-in-real-ear (MIRE) methods for the measurement of the insertion loss of active and passive circumaural earmuffs, helmets, and communications headsets, and specifies acoustic test fixture (ATF) methods for the measurement of the insertion loss of active and passive earplugs, earmuffs, helmets, and communications headsets. The required test fixture has recently become commercially available and laboratories are gaining experience making these measurements. Impulse peak insertion loss data will be presented for a variety of hearing protector types along with a description of the measurement procedure.

Noise Reduction Ratings

Noise Reduction Rating (NRR) is a unit of measurement used to determine the effectiveness of hearing protection devices to decrease sound exposure within a given working environment. Classified by their potential to reduce noise in decibels (dB), a term used to categorize the power or density of sound, hearing protectors must be tested and approved by the American National Standards (ANSI) in accordance with the Occupational Safety & Health Administration (OSHA). The higher the NRR number associated with a hearing protector, the greater the potential for noise reduction.

Why Hearing Protection is Important

Unlike many other injuries, an injury to your hearing from loud noise is a permanent injury. Hearing loss can never be recovered. There is no surgery, nor hearing aid, that can repair the damage caused by loud noise.

Not all loud noise results in a permanent hearing lose. Hearing loss is dependent on both the loudness of the noise and the duration of the exposure. Short-term exposure may only have a temporary effect on hearing, such as causing a decreased ability to hear or causing a ringing in the ear. A short-term hearing problem may clear up within a few minutes or hours after the exposure to the noise ends. However, hearing damage is cumulative. Repeat exposures can lead to:

  • Limited ability to hear high frequency sounds.
  • Limited ability to understand speech.
  • Problems understanding and communicating with others.
  • Permanent hearing loss.