You only want to measure a room, but first you haul a laptop, a measurement mic, an audio interface, and the cables to tie them together, then snake it all across the floor. Plenty of people stall on that setup and never open REW. Whether a phone can stand in for it, and how far that stand-in actually goes, is worth splitting out honestly.
The short answer
It depends on the job.
- If you can sit at a desk and want to chase distortion and multi-position averaging, use REW. No other free tool packs this many features. It’s the de facto standard for desktop measurement.
- If you’d rather skip the PC and carry your measurement into the room — RT60, frequency response, low-end room EQ, on the spot — use Sonir. It runs on the phone alone.
- In practice they’re less rivals than a division of labor. Desk-bound: REW. On location: Sonir.
Expect a full replacement for REW and you’ll be disappointed. What reaches and what doesn’t is clear-cut, so let’s start there.
What REW does well
REW is the reference for desktop measurement. It’s free, and it covers RT60, waterfall, frequency response, plus distortion (THD), multi-position spatial averaging, and target-matched PEQ filter generation. It reads calibration files for measurement mics like the UMIK in full. There’s a reason people say “just measure it in REW and you’re fine.”
The constraint is a single one: it’s desktop. Measuring a room means bringing a laptop, an audio interface, a measurement mic, and cables, then setting it all up. Fine for your own listening room, less so for a quick measurement at a friend’s place, a shop, or a rental you’re scouting. “When in doubt, REW” still holds.
How far a phone reaches
Sonir folds that whole setup into the phone. Play one sweep through the speakers and record it; Sonir pulls the impulse response (IR) and computes RT60, EDT, C50, frequency response, and waterfall automatically. For the low end (20–300 Hz) it builds a PEQ from the difference between the measured response and your target, and exports it in REW or Equalizer APO format. Load a calibration file (.txt) and it corrects the built-in mic’s coloration too.
It also does things REW doesn’t. Sonir isn’t only measurement: you can overlay recordings in A/B or tell them apart in an ABX blind test, all in one place. REW is a tool for measuring a room; it doesn’t line up two recordings to compare them. That’s less mobile turf than the gap Sonir is built to fill.
The comparison
The same “measure the room, then EQ it,” lined up on desktop REW versus phone-based Sonir.
| Item | REW (desktop) | Sonir (phone) |
|---|---|---|
| RT60 / EDT / C50 | ◎ standard | ○ auto from sweep→IR |
| Frequency response | ◎ | ○ |
| Waterfall | ◎ | ○ |
| Automatic PEQ | ◎ many bands, full range | ○ low-end focus (20–300 Hz), needs calibration |
| PEQ export | ◎ many formats | ○ REW / Equalizer APO |
| Calibrated mic | ◎ full UMIK support | ○ calibration file (.txt) |
| Distortion (THD) | ◎ | × |
| A/B & ABX of recordings | × | ◎ |
| Gear needed | PC + interface + measurement mic + cables | one phone |
| Portability | × stationary | ◎ on location |
| Platform | Windows / Mac / Linux | iPhone / iPad / Android |
| Pricing | free | free core + Pro |
Distortion, multi-position averaging, and free full-range PEQ go to REW. Zero-gear measurement on location and recording comparison are Sonir only.
Where a phone can’t cover
To be straight about it: not all of REW lives on a phone. Distortion (THD) measurement isn’t in Sonir. The PEQ is low-end focused, so you don’t place filters freely up through the mids and highs the way REW lets you. That’s partly a deliberate call: the mids and highs swing with listening position, and pinpoint correction there tends to make things worse. Moving the mic to take a proper spatial average is also more mature in REW.
You still can’t get absolute SPL from a phone alone. Load a calibration file and run consistent conditions and relative measurement reaches usable accuracy, but trusting an uncalibrated built-in mic as an absolute value is a mistake. Same caveat in any phone app.
As an aside, once I tried a multi-position average in REW and the cable snagged on furniture every time I moved the mic; I gave up and settled for two points. Better features don’t mean much if you can’t actually reach them on site.
Picking by use case
- Building a serious stationary rig: REW + measurement mic. Most features for free, distortion and multi-position averaging included.
- No PC, RT60 through room EQ on location: Sonir. One sweep covers it from the IR, and the low-end PEQ exports in REW / APO format.
- Measure, then also compare recordings: Sonir. A/B and ABX in the same place.
- Feed a REW “prescription” (PEQ) to a receiver: measure in Sonir, hand the exported PEQ to REW or APO — that combo works too.
It’s not really either/or: cover the field with Sonir and settle in with REW. A phone won’t fully replace REW, but it stands alongside it as a different value — the measurement tool that’s actually in your hand when you need it.
FAQ
Can a phone fully replace REW?
No. REW still wins on distortion measurement, free full-band PEQ, and mature multi-position averaging. But for the everyday range — RT60, frequency response, and low-end room EQ — Sonir reaches usable accuracy on a phone alone.
REW is free, so why use a phone app at all?
Gear and place. REW assumes a PC, an audio interface, a measurement mic, and cables. Sonir runs on the phone you already carry, so you can measure a room on the spot. You trade feature breadth for mobility.
Can I hand my phone-measured PEQ to REW?
Yes. Sonir exports PEQ in REW (Filter Settings) and Equalizer APO formats. Measure on the phone, then drop the filters into your playback chain or a REW project.
Does room EQ work without a calibrated mic?
For spotting low-end trends, the built-in mic shows the shape. But Sonir’s automatic PEQ assumes calibration, and only becomes trustworthy as a real correction once you load a calibration file (.txt). Without it, treat the result as a rough guide.
Related posts
- Measuring room acoustics with a smartphone: the complete guide: the full picture from sweep→IR to RT60, frequency response, and waterfall
- Best acoustic measurement apps: how to pick one that does RT60: a roundup that also covers other mobile and desktop options
Measure it with Sonir
Sonir is an app that completes acoustic measurement and comparison on your phone. The RT60, frequency response, and low-end room EQ in this article come straight from the IR — just play a sweep and record. Export the low-end PEQ in REW / Equalizer APO format, and line up recordings in A/B or ABX. Core measurement is free; per-band depth is Pro.
iOS / Android, coming soon. See the features page for more.