Duration is typically measured over a workday and accumulated through many years. The noise level is therefore expressed in decibels (dB) on the 'A' scale, or dB(A).ĭuration of exposure is equally important. Most workplace noises include a wide band of frequencies and are measured through the 'A' filter in sound-level meters. Sounds must also be specified in terms of frequency or pitch. Hearing protection should be used for any level over 85 dB and double protection for any level over 105 dB. In other words, sound intensity doubles every 3 dB. But 93 dB is still twice as much noise as 90 dB. A sound 1,000 times more powerful than near total silence is 30 dB.įor example, a backhoe and a compressor each producing 90 dB have a combined output of 93 dB, not 180. A sound 100 times more powerful than near total silence is 20 dB.

A decibel is a logarithmic value to the base 10. The A-weighting curve has been widely adopted for environmental noise measurement, and is standard in many sound level meters. When acoustic (calibrated microphone) measurements are being referred to, then the units used will be dB SPL referenced to 20 micropascals 0 dB SPL.

It is normally measured using the A scale, which approximates the human ear’s response to a wide range of frequencies. A-weighted decibels are abbreviated dB(A) or dBA. On the decibel scale, the smallest audible sound (near total silence) is 0 dB. Decibel: Named after the inventor Alexander Graham Bell, a decibel (dBA) is the unit used to express the intensity of sound. This means that noise levels can't be added directly like other numbers. The decibel scale is not linear but logarithmic. Decibel (dB) is the unit used to measure a sound's strength.

Dba decibel scale