If you can take a clear photo, you can take a useful sound measurement. This guide walks you through reliable measurements with either a phone app or a dedicated sound level meter, and it explains how to document results so they’re helpful later.
Pick your tool
Phone apps are fine for relative comparisons and quick checks. Choose an app with A/C/Z weighting and Fast/Slow time response. For safety or compliance, use a calibrated meter with a windscreen and, ideally, a 94 dB calibrator.
Choose settings before you measure
- Weighting: A for general noise; C for bass‑heavy sources.
- Time response: Fast for transients; Slow to stabilize; LAeq for time‑average.
- Range: If your meter supports ranges, pick one that keeps the needle in the middle.
Placement and technique
- Hold the mic at ear height in the listening position.
- Point the mic as recommended by the manufacturer (often toward the source).
- Outdoors, use a windscreen; even light wind can cause spikes.
- Indoors, stand back from walls to avoid reflections skewing the reading.
Log what matters
Write down the location, date, weighting, time response, distance to source, and the reading(s): Max, Min, and LAeq for at least 30 seconds. If you’re comparing changes—like closing a door—measure both states with the same setup.
Calibrate or sanity‑check
If you have a calibrator, check 94 dB before and after a session. No calibrator? Compare two apps or meters side by side. Consistency matters more than absolute perfection for many use cases.
Worked example: quiet room vs AC on
Room idle: 33–36 dB(A) Slow, LAeq 34 dB over 60 seconds. AC on: 41–44 dB(A), LAeq 42 dB. The AC adds roughly 8 dB; perceived loudness about doubles. The record now helps you decide whether simple fixes (filters, isolation pads) made a difference later.
Common mistakes
- Using the wrong weighting for the source.
- Measuring too close to a reflective surface.
- Capturing too short a sample; spikes can mislead.
- Forgetting to document distance and settings.
Turning measurements into actions
With reliable numbers, you can evaluate changes—moving a noisy device further away, adding a soft barrier, or scheduling loud tasks when people aren’t nearby. The meter is a decision tool, not just a scorekeeper.