DecibelwerkQuick answer: If you need a free, no-frills meter for workplace noise dose, use the NIOSH Sound Level Meter: it’s free, built with NIOSH, and reports TWA and dose under both NIOSH and OSHA rules. Decibelwerk is for everyday measuring at home, at gigs and with neighbours: an easy-to-read VU meter, noise logs with PDF reports, a tone generator and a speaker cleaner, with the meter free and Pro for logs beyond three.
At a glance
| NIOSH Sound Level Meter | Decibelwerk | |
|---|---|---|
| Price | Free, no in-app purchases | Meter, tone generator and speaker cleaner free; Pro $19.99 once, $9.99/yr or $1.99/wk |
| Weighting | A, C, Z | A free; C and Z with Pro |
| Readouts | Level, LAeq, Max, Peak, TWA, dose, projected dose | Live level on a VU needle, Leq, Min, Max, NIOSH safe time |
| Logging | Measurement sessions with sharing | Once-a-second logs up to 8 hours, with L10 and L90 |
| Reports | Shares data | One-page PDF report (Pro) |
| External microphone | Supported (Type 2 with a calibrated mic) | Built-in microphone |
| Calibration | Yes | CAL knob, ±10 dB in 0.5 dB steps (Pro) |
| Tone generator | No | Yes, 20 Hz–20 kHz |
| Speaker water cleaner | No | Yes, 165 Hz pulsed |
Details for the NIOSH app come from its App Store listing, checked November 2026.
When the NIOSH app is the better choice
- Occupational noise. Its TWA, dose and projected dose under NIOSH and OSHA rules are exactly what a safety officer or a worker checking a shift needs.
- Professional accuracy. With a calibrated external microphone it meets Type 2 requirements, which a phone’s built-in microphone alone can’t claim.
- Zero cost. No purchases at all.
When Decibelwerk fits better
- Neighbour and home noise. Logs that run all night, label by room, and turn into a PDF with Leq, Max, L10 and L90: the numbers a landlord or noise team asks for. See measuring noise from neighbours.
- Music and gigs. A VU needle you can read at a glance in a dark room, and the NIOSH safe time for the current level.
- Audio tools in one place. A tone generator to test speakers and headphones, and a speaker cleaner for when your phone gets wet.
Use both
There’s no harm in having both: the NIOSH app for a work shift’s dose, Decibelwerk for everyday measuring, logs and audio tools. For tips that make any meter app more accurate, read how to measure decibels on iPhone.