Comparison
dB Decibel Compared with the NIOSH Sound Level Meter
These two apps are not really competitors, and pretending otherwise would be dishonest. One is a validated reference from a federal research institute. The other is a working tool built around what happens after the reading.
Start here
If you want the most trustworthy number, use the NIOSH app
The NIOSH Sound Level Meter is published by the US National Institute for Occupational Safety and Health. It is free, it carries no ads and no in app purchases, and NIOSH tested it in their own acoustics laboratory and report it as accurate within ±2 dBA against a reference meter. They also state it meets the Type 2 requirements of IEC 61672 when used with a calibrated external microphone.
dB Decibel has no independent accuracy validation. Its own calibration screen tells you to use the NIOSH app as your reference, which is the honest position for a small independent app to take. If a single trustworthy number is the whole job, the NIOSH app is the right download and this page has done its work.
Side by side
The three facts that are actually comparable
| dB Decibel | NIOSH Sound Level Meter | |
|---|---|---|
| Publisher | An independent developer | US National Institute for Occupational Safety and Health |
| Published accuracy validation | None | Within ±2 dBA against a reference meter, tested in the NIOSH acoustics laboratory |
| Cost and ads | Free to download with a banner ad, plus one optional one time Pro purchase that removes it | Free, no ads, no in app purchases |
Only rows that can be stated from published sources are listed. Feature by feature rows are deliberately left out: app feature sets change between releases, and a comparison table that goes stale is worse than no table.
The difference in purpose
What dB Decibel is built around
Not a better number. What happens once you have one, and knowing when there is not a number to be had.
Refusing bad readings
Near silence is reported instead of a number when the level sits at or below the microphone floor plus a 3 dB margin, and a clipping flag latches once three consecutive audio buffers reach 0.99 of full scale. Both are in the free version. See measuring bedroom noise at night for why the first one matters and how loud is a concert for the second.
The document at the end
Evidence Mode records timestamped noise events with peak level and duration and exports a PDF and a CSV for a landlord or an association. Sleep Soundscape logs a night and summarises the quietest hour, the loudest hour and a disturbance count. Both are part of Pro. See documenting a noisy neighbor.
Analysis beyond a level
Leq, L10 and L90 in the free version. In Pro: A, C and Z weighting built from the IEC 61672 filter specification, octave bands from 31.5 Hz to 16 kHz, a real time spectrum analyzer, a test tone generator, and on device sound identification using Apple's built in classifier.
Living on the phone
Start and stop from Siri, the Action Button and Control Center in the free version. A Live Activity with Lock Screen and Home Screen widgets, session history with auto save, loud level alerts, and per input trim for external and Bluetooth microphones are part of Pro.
Choosing
A straight recommendation
- Use the NIOSH app
- when the number itself is the deliverable, when you are doing occupational work and want the tool published by the occupational agency, when you want something with a published validation behind it, or when you want a free meter with no ads at all.
- Use dB Decibel
- when you need a log rather than a reading, when the room is quiet enough that a false 55 dB would mislead you, when the sound is loud enough that clipping is a real risk, when you want a night recorded and summarised, or when you want octave bands and a spectrum on a phone.
- Use neither
- when the measurement has to hold up: a legal dispute, an occupational assessment, a regulatory limit, anything medical. Both are phone apps. That work needs a certified Class 1 or Class 2 sound level meter, a field calibrator check, and somebody qualified to run it.
Running both is entirely reasonable, and is in fact what dB Decibel's calibration flow suggests: take the reference from the validated app, then work in the one that keeps the record.
What this app is not. Readings are approximate (±dB) and come from an uncalibrated phone microphone. dB Decibel is an environmental sound measurement tool. It is not a certified sound level meter, not a dosimeter, not hearing protection and not a medical device, and it is not suitable for occupational, regulatory or legal compliance. That wording is taken from the disclaimers inside the app itself. dB Decibel is not affiliated with, endorsed by or connected to NIOSH or the CDC. Their app is described here from their own published material.
Get the app
Try the part that is different
The near silence flag, the clipping flag, live dB(A) with peak hold and Leq, L10 and L90 are all in the free version, so you can hold it next to any other meter and see where they disagree. Everything runs on the device and audio is never recorded or sent.
Free to download. iPhone, iOS 18 or newer. Optional one time Pro unlock, no subscription.Keep reading