Sound facts on noise in an occupational setting

21 September 2022


Measuring sound is generally concerned with noise and our exposure to it.  So, what is noise? Noise in an occupational setting is regarded as unwanted or damaging sound.

Acceptable standards

Victoria’s noise exposure standard is a level of 85 decibels ‘averaged’ over an eight-hour period, and a peak level of 140 decibels. The standard relates to noise measured at the employee’s ear.

Here are some common sounds and their decibel levels:

Leaves rustling                                   20 dB

Whisper                                               30 dB

Normal conversation                       60 dB

Traffic                                                   70 dB

Power tools                                         90 dB

Music concert                                   110 dB

Jet airplane taking off                    120 dB

Jackhammer or gunshot               130 dB

Common parameters

Here are some common parameters for measuring noise in an industrial setting:

  • LEP,d is a worker’s daily exposure to noise at work (normalised to an 8 hour day), taking into account the average levels of noise and the time spent in each area
  • Lmax and Lmin parameters are quite easy to understand. They are simply the highest and lowest values measured by the sound level meter over a given period of time
  • Ln, where n may be anything from 1 to 99, is the noise level exceeded for n% of the measurement time. Two common values are L90: This is frequently taken as the Lp of the background level i.e. exceeded for 90% of the time; and, L10: This value is the level exceeded for 10% of the time and takes account of any annoying peaks of noise. L10 is frequently used when assessing traffic noise and in planning applications.

Equipment types

The class of sound meter is important to understand. International Electrotechnical Commission (IEC) standards divide sound level meters into two “classes”, which have the same functionality, but different tolerances for error.  Class 1 instruments have a wider frequency range and a tighter tolerance than the lower cost, Class 2 units. This applies to both the sound level meter itself, as well as the associated calibrator.

Check out some ACOEM smart noise monitoring and analysis instruments on offer by HydroTerra.