Measurements · Noise
Average Level (Lavg)
Also known as average sound level
Average sound level (dosimeter, exchange-rate dependent).
What it is
What is Lavg (average sound level)?
Lavg is an average sound level over a period, but with a distinctive convention: it is integrated using a 5 dB exchange rate, the rule used in United States occupational noise regulation by OSHA and MSHA. The exchange rate governs how a change in level trades against a change in duration for equal exposure: a 5 dB rate means that every 5 dB increase halves the allowable time. This makes Lavg subtly different from Leq, the equivalent continuous level, which uses a 3 dB (equal-energy) exchange rate followed almost everywhere else and in environmental work. The two describe the same fluctuating noise but weight intermittent loud periods differently.
Lavg is therefore best understood as the US hearing-conservation counterpart to Leq: an energy-style average, but with a more forgiving trade-off between level and time.
Band resolution: reported broadband plus 1/1 octave and 1/3 octave. The metric and its frequency band are independent. Check the sound-capable devices below for what each one reports.
Health and operational effects
Like Leq, Lavg is used to quantify a worker's noise exposure for hearing conservation, feeding directly into the time-weighted average and noise dose that determine whether hearing protection, audiometric testing, and a formal hearing conservation program are required. Because the 5 dB exchange rate discounts brief loud excursions more than the 3 dB rate does, an intermittent noise environment can produce a lower Lavg (and therefore a lower assessed exposure) than the same noise evaluated as Leq. Understanding which exchange rate applies is essential, because the choice materially changes the result and the compliance conclusion.
For employers operating under US occupational rules, Lavg is the average that underlies the dose calculation, so getting the exchange rate and criterion level right is a compliance fundamental.
How it is measured
How Average Level (Lavg) Is Measured
Lavg is produced by a noise dosimeter or sound level meter built to the IEC 61672 standard, configured with the 5 dB exchange rate and the criterion level set by the applicable regulation. Because this configurable, occupational-grade measurement goes beyond a simple ambient sound reading, it is made with an external IEC 61672 instrument logged on a Thiamis gateway, which can also report the anchor metric Leq for comparison. Many instruments compute Lavg (5 dB) and Leq (3 dB) simultaneously, so the effect of the exchange rate is directly visible.
An instrument on Thiamis1
A third-party instrument connected to a Thiamis gateway, reporting into the same Environet account.
Placing noise monitors
For personal exposure the dosimeter microphone is worn in the worker's hearing zone, on the shoulder near the ear, capturing the noise the person actually receives across the shift. For area measurement the microphone is placed at the position of interest, clear of reflecting surfaces, and fitted with a windshield where needed. As Lavg is intended to represent a person's working exposure, wearing the instrument through a full and typical shift is what makes the result meaningful.
Every device and option that measures Average Level (Lavg) 1
| Device / option | Type | Base platform | Measures |
|---|---|---|---|
 TSI · SP-SE-1, SP-SE-1-1/1, SP-SE-1-1/3… | Noise Monitors | Thiamis |
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Questions
Average Level (Lavg) FAQ
What is an exchange rate, and why does it matter?
The exchange rate is the number of decibels by which the level must rise to halve the allowable exposure time for the same dose. A 3 dB rate treats noise on an equal-energy basis and is used for Leq and environmental work; the 5 dB rate used for Lavg is more lenient toward intermittent loud noise. Because it changes the calculated exposure, the rate must always be stated.
How is Lavg different from Leq?
They are the same kind of energy-style average but use different exchange rates: Lavg uses 5 dB, Leq uses 3 dB. For steady noise they nearly coincide, but for intermittent noise Lavg tends to read lower. Which one applies depends on the regulation being followed.
Which one should I be using?
US occupational compliance under OSHA and MSHA is based on the 5 dB exchange rate and therefore Lavg, TWA, and dose. Most other jurisdictions and virtually all environmental assessment use the 3 dB equal-energy basis and Leq. The applicable standard dictates the choice.
How do I monitor Lavg?
Lavg needs an external IEC 61672 dosimeter or sound level meter on a Thiamis gateway, configured with the correct exchange rate and criterion level, and it can log Leq at the same time for comparison. Use the configurator to combine noise with the other parameters your program requires.
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