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Sonarworks Reference 4 Studio Edition Review at Sound on Sound

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Sonarworks software has been widely lauded for its ability to correct the sound of headphones. Can it do the same for monitors?


  • Slick and satisfying to use.
  • Effective and instructive.
  • Achieves what it sets out to do.


  • Needs thought and care.
  • Not a substitute for quality monitoring properly installed in a well-behaved room.


Sonarworks 4 is a persuasive and powerful solution to a common problem and it’s really hard to fault the way it works. But to my mind it ought to be the tool you turn to, and use thoughtfully, after you’ve got your existing room and monitoring working as well as possible — not before.

Room For Improvement

If we were all lucky enough to work in studio rooms of infinite size, or in rooms with boundaries that offered perfect absorption of acoustic energy, there’d be no need for applications like Sonarworks to compensate for room acoustics because we’d always hear just the flat, direct sound from the monitors. In the real world, however, we hear not just the direct sound energy that leaves the monitors, but also energy reflected from the room boundaries. And that reflected energy will be imprinted with both the off‑axis response of the monitors and the particular absorption characteristics of the room boundaries it has reflected from.

The way our ears and brain deal with these multiple arrivals of sound energy depends firstly on how far apart in time they are, and secondly on their relative levels. Reflected sound that arrives within a few milliseconds of the direct sound, known as early reflections, will be integrated by the brain, and although the direct sound will still dominate, the tonal character perceived for the audio event will be a composite of the direct sound and early reflections. But reflected sound, thanks to the fact that it has travelled further and is delayed, will also interfere with the direct sound. Sometimes the interference will be constructive, and a response peak will result, and sometimes it will be destructive, which will result in a response dip. It is these peaks and dips that Sonarworks aim to equalise and flatten.

Along with boundary reflections, real‑world rooms also play host to resonant standing waves, defined generally by the distance between room boundaries, and these will result in significant peaks and troughs in volume level at different locations in the room. We’ve all no doubt experienced the phenomenon of moving the listening chair back away from the monitors and finding that the volume level of specific low frequencies changes. That’s a result of standing waves between room boundaries. Standing waves will occur at frequencies where the dimension between boundaries equals half the wavelength (and multiples of it), and it’s not rocket science to do a quick measurement of your studio room dimensions to identify some frequencies that might cause trouble.

My room, for example, has a ceiling‑to‑floor dimension of 2.5m. Knowing that the first standing‑wave frequency can be calculated through dividing the speed of sound (343m/s) by twice the room height (ie. half the wavelength), I ought to expect one series of standing waves starting at 68.6Hz. The side walls and end walls will, of course, also potentially create standing waves. As illustrated on the room mode calculator at, there are multiple potential standing‑wave modes in any given room. Like fingerprints, no two rooms are ever the same. As with the response anomalies caused by early reflection interference, Sonarworks attempts to equalise the effects of low‑frequency standing waves at the listening position.

In Your Head

Describing the basics of room acoustics in just a few paragraphs is possible only by lightly scratching the surface and by almost completely ignoring the field of psychoacoustics. For example, I wrote that the brain integrates direct sound and early reflections and perceives a composite tonal balance. Well, whole books have been written on that subject alone, so when we consider using technology such as Sonarworks to ‘correct’ for room acoustics, it’s important to appreciate that while the technology may be able to flatten the measured frequency at the listening position, doing so begs a whole host of deeper psychoacoustic questions.

So far I’ve majored on discussing room acoustics, but Sonarworks also corrects monitor frequency response anomalies. Just as with psychoacoustics, there’s no shortage of pages on the myriad phenomena that might cause a speaker to have a non‑flat frequency response, so I’m not going to head off down that diversion now (maybe that’s the subject of some future feature). We, after all, have lives to lead and more important things to do.

Be sure to check out the full review over at

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