Decibel Sound Meter What is LAeq in noise measurement? The average noise level, with real numbers
LAeq is the A-weighted equivalent continuous sound level: the steady level that would carry the same sound energy as the noise you measured over that time. Because it averages energy rather than decibel numbers, loud moments weigh far more than quiet ones. In Decibel Sound Meter it is AVG on the meter and LAeq in the Exposure tab.
What does LAeq stand for?
- L: level, in decibels.
- A: A-weighted, the frequency curve from IEC 61672 that follows how human hearing responds, so the result is in dBA.
- eq: equivalent continuous, one steady number for a period that actually varied.
- A duration may follow, as in LAeq,8h for 8 hours or LAeq,T for a period T.
The equivalent continuous sound level formula
LAeq = 10 × log10( Σ 10^(Li/10) × ti ÷ Σ ti )
Each level is turned back into energy, weighted by how long it lasted, averaged over the whole time and turned back into decibels. A plain average of the decibel numbers skips that energy step, which is why it comes out lower.
Why is LAeq higher than the simple average?
| Noise pattern | Simple mean | LAeq |
|---|---|---|
| 30 min at 70 dB + 30 min at 90 dB | 80.0 dB | 87.0 dB |
| 50 min at 60 dB + 10 min at 90 dB | 65.0 dB | 82.2 dB |
In the second row, ten loud minutes out of sixty lift the LAeq more than 17 dB above the simple mean. That is the point of it: strain on the ears comes mostly from the loud parts, and LAeq doesn't let a long quiet stretch hide them.
Every 3 dB is roughly double the energy, and 20 dB is 100 times the energy, so 90 dB carries 100 times the energy of 70 dB.
Where do you see LAeq in the app?
| Where | Label | Shown as |
|---|---|---|
| Meter tab while recording | AVG | Whole dB |
| Exposure tab | LAeq | dBA with 1 decimal |
| History > Measurement Details | Average | Whole dB |
| PDF report and CSV | Average in the summary | Whole dB in the PDF, 1 decimal in the CSV |
How to measure LAeq with your phone
- For a quick average of a room or event: on the Meter tab tap Start Recording, wait, read AVG, then Stop Recording and Stop & Save.
- For a longer period in dBA with one decimal: open Exposure, tap Start Exposure Measurement and read LAeq next to SPL now. Stop & Save Session keeps it in Sessions.
- To look at the data yourself, open the recording in History and use Export as CSV, which lists the level sample by sample with a summary.
LAeq 8h vs TWA
TWA (time-weighted average) is the steady 8-hour level that would give the same noise dose. With the NIOSH 3 dB exchange rate and everything above the 80 dBA threshold, TWA and LAeq over 8 hours are practically the same number. With the OSHA 5 dB exchange rate they differ, because OSHA halves the allowed time every 5 dB, not every 3.
| Measure | Result |
|---|---|
| LAeq over the 3.5 hours measured | 89.5 dBA |
| LAeq over 8 hours (LAeq,8h) | 85.9 dBA |
| NIOSH TWA (8 h) | 86.0 dBA |
| OSHA TWA (8 h) | 83.0 dBA |
Unrounded, the two differ by only 0.02 dB (85.95 against 85.97); the rounding makes it look like 0.1. The tiny gap exists because 3 dB is a rounded doubling of energy. The Exposure tab shows both side by side: LAeq for the time measured and TWA (8 h) scaled to a working day.
Questions and answers
What is the difference between LAeq and dBA?
What is LAeq 8h?
What is the difference between Leq and LAeq?
Is the AVG on the meter an LAeq?
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