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APPENDIX E

Glossary

297

Dose, ProjDose: The Noise Dose is the equivalent averaged A-weighted Noise Level (taking

the Threshold Level into account) using Exchange Rate = 3 for an 8 hour

period (reference duration) relative to the maximum allowed (the Criterion

Level) – expressed in percentage.

Example: If the Criterion Level is 85 dB and a person is exposed to a constant

sound pressure level of 85 dB for 8 hours, then the Dose is 100%. A constant

level 88 dB results in a Dose of 200% and a constant level of 82 dB results

in a dose of 50%.

The Projected Dose is the Noise Dose based on measurement duration less

than 8 hours, assuming the sound level for the remaining time stays the same.

DoseUQ, ProjDoseUQ: The Noise Dose is the averaged A-weighted Noise Level (taking the

Threshold Level into account) with Time Weighting U = F or S and Exchange

Rate Q = 4, 5 or 6 for an 8 hour period (reference duration) relative to the

maximum allowed (the Criterion Level) – expressed in percentage.

Example: If the Criterion Level is 90 dB and a person is exposed to a constant

average sound level of 90 dB for 8 hours with Time Weighting S and

Exchange Rate 5, then the DoseS5 is 100%. A constant level 95 dB results

in a DoseS5 of 200% and a constant level of 85 dB results in a doseS5 of

50%.

The Projected DoseS5 is the Noise DoseS5 based on measurement duration

less than 8 hours, assuming the sound level for the remaining time stays the same.

E: Sound Exposure is the energy of the A-weighted sound calculated over the

measurement time. The unit is Pa

Exchange Rate: Exchange Rate is the increase in noise level that corresponds to a doubling

of the noise level. The Exchange Rate is used for calculation of L

avUQ

, TWA,

TWA

, DoseUQ and ProjDoseUQ, where U = F or S and Q = Exchange

Rate: 4, 5 or 6 dB.

Note: L

Aeq

is always based on an Exchange Rate = 3.

Exposure Time: Exposure Time is the actual time that a person is exposed to noise during

a workday. Used for calculation of L

ep,d

and L

ep,d,v

Fast Max: Maximum time-weighted acceleration or voltage level measured with Linear

frequency weighting and Fast time weighting. It is the highest level occurring

during the measurement time.

Fast Min: Minimum time-weighted acceleration or voltage level measured with Linear

frequency weighting and Fast time weighting. It is the lowest level occurring

during the measurement time.

‘F’, ‘S’ or ‘I’ time

weighting:

A time weighting (sometimes called a ‘time constant’) defines how the

exponential averaging in root-mean-square (RMS) measurement is done. It

defines how the heavily fluctuating sound pressure variations are smoothed

or averaged to allow useful readings. The standards define three time

weightings: F (Fast), S (Slow) and I (Impulse). Most measurements are

carried out using the ‘F’ time weighting, which uses a 125 ms time constant.

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