Noise Exposure: Level, Duration and Hearing Safety

Why level and duration combine

Hearing dose works like an energy budget: a brief very loud event and a long moderate sound can carry similar risk. A single peak reading such as 100 dBA says little on its own — three hours at that level is a different matter from three seconds. That is why this meter records duration alongside current, minimum, energy-average Leq and maximum values, and why exposure thinking always starts from the average over the full period, never from one instant. See how the meter works for what each statistic means.

The 3 dB exchange rule

A 3 dB increase doubles sound energy, so widely used hearing guidance halves the recommended daily time for every 3 dB above 85 dBA: 8 hours at 85 dBA, 4 hours at 88 dBA, 2 hours at 91 dBA, 1 hour at 94 dBA, 30 minutes at 97 dBA and about 15 minutes at 100 dBA. Below roughly 70 dBA, ordinary daily sounds such as conversation near 60 dBA are not an exposure concern. Compare your readings with the decibel comparison chart to place them on a familiar scale.

Recommended exposure table

These are widely published screening bands for personal awareness, not a medical assessment of any individual. Some workplace regimes use different exchange rates and legal thresholds, which is why personal checks and formal compliance measurements are different tasks.

Everyday awareness versus occupational compliance

For home, leisure and personal choices, an approximate browser reading is enough to act on: sustained levels near or above 85 dBA mean shortening the time or using hearing protection. Workplace assessments are stricter by design — exposure monitoring, hearing conservation programmes and engineering controls with calibrated Class 1 or Class 2 instruments. A phone or laptop microphone cannot substitute for that process. Read accuracy and limitations before drawing any formal conclusion.

Checking your own exposure with this meter

1. Calibrate once against a known reference so the offset is device-specific.
2. Measure each noisy period in full — commute, gym, workshop — following how to use the meter.
3. Note the Leq and duration of each period, then record repeats or export CSV or JSON for your records.
4. Reduce the loudest period first: every 3 dB saved doubles the safe time.

Two afternoons, two doses: worked screening math

Saturday you mow for 45 minutes and the meter holds a 91 dBA Leq. The table allows about 2 hours at 91, so that single chore eats roughly a third of the day's budget — fine on its own, tight if a loud dinner follows. Sunday you sit in a cafe where the meter settles near 72 dBA across a full hour. Below roughly 70 dBA ordinary sounds stop being an exposure worry, so 72 for an hour barely registers. Contrast that with a 20-minute concert encore averaging 99 dBA: the guidance lands near 15 minutes at 100 dBA, so those 20 minutes already overshoot. Your move in each case comes from Leq plus duration together. A 99 dBA peak that lasts four seconds while you drop a pan matters far less than 88 dBA sustained through a four-hour rehearsal, even though the bigger number grabs your eye.

What to do when the display hovers near 85 dBA

Treat 83–86 dBA as your amber zone. First calibrate once so the offset is device-specific, then run Slow response for the whole activity and read Leq, not the dancing current value. If a workshop grinder holds 88 dBA, you have about 4 hours before the screening budget runs out; trimming the source 3 dB — stepping back, closing a door, fitting a muffler — stretches that to roughly 8. Doubling distance outdoors cuts near 6 dB, which quadruples allowable time. Earplugs or muffs at a gig, lower headphone volume with breaks every hour, and a quiet rest after ringing ears all count. Anything you log here stays personal screening: formal workplace calls belong on Class 1 or Class 2 hardware with its own programme, a point expanded in accuracy and limitations.

Screening mistakes that hide the real dose

• Logging the peak instead of Leq — a 102 dBA clap tells you nothing about the two-hour average that sets risk.
• Sampling five seconds of a variable room — run 30–60 seconds minimum and keep the full duration on screen.
• Quoting decimals from an uncalibrated phone — round to whole dBA and re-check with a known reference before acting.
• Measuring from a pocket or bag — fabric and body shielding can under-read 5 dB or more; set the mic free at ear height.
• Adding periods by ear instead of by numbers — note each Leq with its duration or export CSV or JSON, then attack the loudest block first since every 3 dB saved doubles remaining time.

Protecting your hearing

Double the distance from a source to cut roughly 6 dB, wear earplugs or earmuffs at concerts and around machinery, keep headphone sessions moderate with regular breaks, and rest your ears after loud events — persistent ringing means the dose was too high. If you notice lasting ringing, muffled hearing or pain, consult a hearing professional rather than relying on any app reading. Our measurement disclaimer explains these limits.

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