Hearing Protection - Glossary of Terms

 Texas America Safety Company
Hearing Protection
Glossary of Terms
"A" Weighting:

'A' weighted measurements are reported in dBA (decible A) and correspond to the way the human ear hears varied speech frequencies. The scale is typically used in both community and industrial noise situations. .

"C" Weighting:

This scale provides a flat frequency response with slight attenuation of the very high and very low frequencies. These measurements are reported as dBC (decible C).


This mark is the symbol of conformity on industrial safety products that have been approved for sale in the European Union (EU). CE conformity indicates that the safety product and systems within the manufacturer's company meet or exceed the established requirements of quality assurance, on-going testing, and user information. All safety products sold in the EU must carry the CE mark.

Continuous Noise:

When intervals of sound waves are less than one second apart


A unit of measure often used as the scale for sound pressure levels (SPL); perceived as "intensity or loudness".

Exchange Rate:

The rate in which sound energy is averaged over time. Using the decibel scale, each time the sound energy doubles, the measured level increases by 3 dB. This is the rate that most of the world uses.

External Ear:

The part of the ear consisting of the Pinna or visible part of the ear and the external auditory canal


The number of cycles of vibration that occur in one second. The number of cycles is designated in Hertz (Hz) and perceived as "pitch"

Impulsive Noise:

Intervals of sound waves are greater than one second apart and characterized by high-amplitude, very short wave

Inner Ear:

Internal part of the ear consisting of cochlea, semicircular canals and auditory nerves

Mean Attenuation:

The average value calculated in each test frequency.

Middle Ear:

The ear drum and ossicular chain (malleus, incus and stapes)


These initials stand for Noise Induced Hearing Loss due to excessive noise exposure.

NRR/Noise Reduction Rating:

Noise Reduction Rating (NRR) is a rating system set up by the Environmental Protection Agency (EPA) as a guideline indicating the amount of potential protection a hearing protection device will provide in a noisy environment. Hearing protection devices are tested using the Real Ear Method as directed by the American National Standard Institute (ANSI) and in accordance with test procedures established by the Acoustical Society of America. Testing is performed in a controlled environment providing posted NRR ratings of how the various products compare with other similar hearing protection products in an uncontrolled noisy environment. However, testing results do not evaluate the devices reusability, adaptability, quality or comfort. Therefore, the bottom line is, the user must make the determination of the best product for specific needs.


This is the visible part of the ear, which, for optimal protection should be completely enclosed by ear muff cups.


Sensory neural hearing loss due to aging


PTS (Permanent Threshold Shift) refers to permanent change in hearing due to continuous noise exposure.


This code is used for the Australian standard for testing of hearing protection products.

Sound Level Meter:

An instrument to measure sound levels consisting of a microphone, a frequency selective amplifier, and an indicator. The meter measures sound level in decibel SPL (sound pressure levels).


SNR (Single Number Rating System) set up by the European Union (EU) is a rating system indicating the amount of potential protection a hearing protection device will provide in a noisy environment. Tests are conducted by independent testing laboratories, meeting all of the regulatory requirements set out by the EU, evaluating both ear plugs and ear muffs.


The presence of ringing, humming, or buzzing in the ear, either intermittent or continuous.


TTS (Temporary Threshold Shift) refers to temporary change in hearing due to noise exposure.

Texas America Safety Company
  4400 Danhil Drive
  Brownwood, TX 76801
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