Search for an app to measure a speaker and you mostly get room measurement apps. That isn’t laziness on anyone’s part. The moment a microphone goes up inside a room, every app is measuring the same thing: the speaker and the room together. So the question worth comparing is not which app measures the speaker most accurately, but which one turns that combined curve into something you can act on.
The short answer
- If you can sit at a desk, REW. Free, the most flexible, and still the reference for speaker work too
- For instrument-grade accuracy on iOS, SignalScope X. Calibration is its day job, subscription pricing
- For a one-time base you’ll use for years, AudioTools. Solid, dated interface
- If sound level and a live display are all you need, Decibel X. It isn’t built to pull an IR out of a sweep
- To measure on a phone and line up left against right, before against after, one speaker against another, Sonir
What “measuring a speaker” actually involves
There are two approaches. Play pink noise and watch the band levels on an RTA, or play a sweep, record it, and deconvolve the recording into an impulse response.
The first is quick, and all you keep is the display. The second leaves you with one signal, the IR, and frequency response, RT60 and the waterfall all fall out of it. Anything on the time axis, such as the arrival-time difference between channels, needs the IR to exist at all. Once the subject is the speaker rather than the room, the field really splits on whether an app can capture an IR.
And that IR has the whole room baked into it. The rough boundary is the Schroeder frequency, around 250 to 300 Hz in a typical room. Below it standing waves dominate, which means the enormous bass peaks and dips are a room story first. No app changes that. There’s more on this in the guide to measuring speaker frequency response with a phone.
Three axes that actually separate them
Since the physics is shared, the differences show up in what happens after the capture.
- Can it capture an IR from a sweep? An app that can’t is a display, not an instrument
- Can it measure left and right separately? You listen in stereo, so one channel’s curve is half the story
- Can you repeat the measurement under the same conditions? Overlaying two curves taken under different conditions tells you nothing
The third one quietly decides most outcomes. Nearly everything people want from speaker measurement is a before-and-after: new isolation feet, the cabinet pulled 10 cm off the wall. In that work, repeatability matters more than the absolute correctness of any single curve.
The comparison
Pricing and feature tiers change, so check the store before buying.
| App | Sweep to IR | Frequency response | Left vs right | Comparing measurements | Calibration file | Pricing | Platforms |
|---|---|---|---|---|---|---|---|
| REW | Yes | Yes | Manual (two passes, overlaid) | Excellent | Yes | Free | Windows / Mac / Linux |
| SignalScope X | Yes (higher tiers) | Yes | No | Limited | Excellent (UMIK) | Subscription | iOS / Mac |
| AudioTools | Yes | Yes | No | Limited (seat-to-seat) | Yes | One-time base + modular IAP | iOS / Mac |
| Decibel X | Not its purpose | Partial (RTA display) | No | No | Partial | Free + subscription/one-time | iOS / Android |
| SpectrumView | No | Partial (spectrum display) | No | No | No | Inexpensive one-time | iOS |
| Sonir | Yes | Yes | Dedicated measurement | Excellent | Yes (.txt) | Free | iPhone / iPad / Android |
App by app
REW
The reference, for speakers as much as for rooms. Free, captures an IR from a sweep, and produces frequency response, RT60, waterfall and group delay. It reads calibration files. There’s no dedicated left-right metric, but measuring one channel at a time and overlaying gets you there. The single constraint is that it needs a computer. Anyone who has balanced a laptop on their knees while the microphone sits 30 cm from a tweeter knows how much that one constraint weighs.
SignalScope X
The choice when instrument-grade numbers on iOS come first. UMIK-class calibration is its core competence, and the higher tiers reach impulse response and reverberation time. Strong if you want the speaker’s response as a trustworthy number. Less so if you want those numbers lined up against each other afterwards. Subscription pricing.
AudioTools
The long-standing iOS measurement app. A one-time base plus the modules you need, with RT60 and calibration among them. The seat-to-seat comparison gets close to measuring several positions and reading them side by side. The interface is old and, honestly, stiff by current standards. It remains a serious tool for people who measure for a living.
Decibel X / SpectrumView
Neither belongs on a speaker measurement shortlist. Decibel X is fundamentally a sound level meter with a live display, not something built around capturing an IR from a sweep. SpectrumView is an inexpensive way to look at a spectrum. Both are useful for eyeballing how tonal balance shifted after you moved something, but that isn’t a measured frequency response.
Sonir
Plays a sweep from the phone, captures the IR, and reports frequency response, RT60, EDT, C50 and the waterfall. The curve is relative, normalised to 0 dB across 300 Hz to 3 kHz with 1/6-octave smoothing. Load a calibration file (.txt) if you need absolute level.
Where it earns its place for speaker work is the other two axes. Left and right have a dedicated measurement: the same rising sweep plays through each channel in turn, and you get arrival-time difference in microseconds, cross-correlation between the two impulse responses, and per-band deviation. When left and right disagree, the cause is usually not unit variation but asymmetric placement. One side closer to a wall, a bookshelf in front of the other, toe-in that drifted.
The other is repeatability. Measurements carry the gear profile, the calibration state and a room tag with them, and trying to overlay two that don’t match raises a warning. It doesn’t block the comparison, because sometimes you want to look anyway.
Picking by use case
- Desk available, want everything for free: REW
- Instrument-grade accuracy on iOS above all: SignalScope X
- One-time base, measuring for years: AudioTools
- Sound level and a live display is enough: Decibel X
- Measure on a phone and line curves up against each other: Sonir
To be straight about it: ranked purely on how accurate a single curve is, Sonir isn’t the top of this list. REW gives you more freedom if you can set up at a desk, and SignalScope has stacked up more instrument credibility on iOS. Sonir earns its place when you want to carry a curve around and put it next to another one.
An aside. I once spent an afternoon convinced a pair of speakers had a 3 dB channel imbalance. It wasn’t the speakers and it wasn’t the microphone: the balance knob on the preamp had been nudged half a notch between the two runs. Suspect the conditions before the equipment. I fully expect to make the same mistake again.
FAQ
Is there an app that measures the speaker alone?
Not while you measure inside a room. What every app produces is a combined curve of speaker plus room plus microphone. That is physics, not a difference in app quality, so the useful question when comparing apps is not which one gets closest to an anechoic curve but which one helps you read differences.
Can’t I just look at pink noise on an RTA?
For a rough sense of tonal balance, yes. But an RTA only displays: no impulse response is kept, so you get no reverberation time and no arrival-time difference between channels. Playing a sweep and deconvolving it into an IR gives you frequency response, RT60 and a waterfall from the same single capture.
Which apps measure left and right speakers separately?
REW handles it by measuring one channel at a time and overlaying the results. Sonir has a dedicated imaging measurement that plays the channels in sequence and reports arrival-time difference in microseconds, cross-correlation between the two impulse responses, and per-band left-right deviation from one run. SignalScope X and AudioTools are instrument-first and carry no dedicated left-right metric.
How far can I get for free?
If a computer is available, REW is free and complete. On a phone, Sonir’s sweep measurement plus frequency response, RT60, waterfall, per-band analysis and overlaying measurements are all free. Decibel X and SoundTools have free tiers too, but neither is built around pulling an IR out of a sweep.
Related reading
- Measuring Speaker Frequency Response With a Smartphone: what that curve actually represents
- Best Apps for Measuring RT60: the same field sorted by room reverberation
- Can a Phone Replace REW?: where desktop still pulls ahead
- How to Compare Speakers A/B Fairly: the three things to keep identical
Measure it with Sonir
Sonir does acoustic measurement and comparison entirely on a phone. The speaker measurement in this article works exactly as described: play a sweep, record it, and the impulse response gives you frequency response and the left-right difference. Everything is free, including per-band analysis and overlaying measurements.
Download on the App Store. Android is coming soon. See the features page for details.