EXHAUST dB METER

KNOW THE TERMS

dB(A) / dB(Z)

A-weighting tilts the reading toward how people hear (it plays down deep rumble). Z is unweighted, so drone and low-end boom count fully. Pick one and stick with it when comparing.

Average (Leq)

The energy average over the whole test, the standard way to average decibels. One loud rev moves it more than a plain average would.

Peak

The loudest 100 ms block. If the phone's microphone hit its limit, the real peak was higher (the result tells you).

Markers

Tap MARK REV when you reach an RPM. Each marker's value is the peak from that tap to the next one, so hold the RPM, then mark the next.

Distance & angle

Sound drops about 6 dB every time you double the distance outdoors. Same spot, same height, same angle, or the comparison is meaningless.

Calibration offset

If you own a trusted reference meter, measure the same sound with both and enter the difference. It shifts every reading by that amount; it doesn't make the phone certified equipment.

HOW THE NUMBER IS MADE

• The browser’s microphone processing (auto gain, noise suppression, echo cancellation) is switched off where the browser allows it; the result tells you if it stayed on.
• Levels are computed 10 times a second. Without calibration, the phone’s digital full scale is assumed to be about 120 dB, typical for phone microphones. Phones differ by several dB.
• Best use: before/after comparisons on the same phone, same spot, same settings.