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Appendix B
Glossary of Terms
Weighting (A, C, Z, etc.)
“A”, “B”, “C”, “Z” and LINEAR are the standard weighting networks available. These are frequency filters that cover the frequency range of human hearing (20Hz to 20 kHz). “A” weighting is the most commonly used filter in both industrial noise applications (OSHA) and community noise regulations. “A” weighted measurements are often reported as dBA. The “A” weighted filter attempts to make the dosimeter respond closer to the way the human ear hears. It attenuates the frequencies below several hundred hertz as well as the high frequencies above six thousand hertz. “B” weighting is similar to “A” weighting but with less attenuation. The “B” weighting is very seldom, if ever, used. The “C” weighting provides a fairly flat frequency response with only slight attenuation of the very high and very low frequencies. “C” weighting is intended to represent how the ear perceives sound at high decibel levels and is often used as a “flat” response when LINEAR is not available. “C” weighted measurements are often reported as dBC. “Z” is zero weighting, with no weighting across the frequency range of human hearing. LINEAR is thought of as having a flat frequency response curve over the entire measurement frequency range. LINEAR is most commonly found on upper model sound level meters and is typically used when performing octave band filter analysis.
Upper Limit (UL)
A type of measurement parameter setting in which the user selects a certain decibel level. The dosimeter will then record the amount of time that the sound level was at or greater than the preset level. This time is then recorded as “UL Time”
Windscreen
A windscreen is a covering for the microphone that reduces disturbances caused by wind and direct contact with other surfaces. The windscreen is placed over the microphone when taking measurements to help prevent false high readings due to wind blowing across the microphone or objects (hair, clothing, etc.) brushing against the microphone. The windscreen will also help protect the microphone from dust and debris.
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