How Automatic Room Correction Can Help (and Hurt) Your Sound System

Speakers sound different when you use them in different rooms. That isn’t rocket science. But figuring out how to make speakers sound their best in a particular room comes pretty close to rocket science. The shape, size, and contents of a room have a huge, and often negative, effect on how an audio system sounds. Correcting for those effects requires a solid understanding of physics, familiarity with some key bits of audio research, and a specialized microphone and audio-measurement software. Fortunately, the automatic room-correction system built into your audio components can do the job for you—but unfortunately, not all room-correction systems do the job equally well.

Room correction is built into most AV receivers, many subwoofers, a few pieces of stereo gear, and even some wireless speakers from Sonos, Amazon, and Apple. The goal is to correct for the effects that a room’s acoustics have on the sound by using microphones to analyze different sounds emitted from the speaker(s) and tailoring the sound accordingly.

A good room-correction system makes the sound more natural and pleasing. The notes in a bassline will have the same level as they do on the original recording. Explosions in movie soundtracks will slam rather than just boom. Movie dialogue will sound more realistic, not harsh, thin, or bloated. The sound may also become more enveloping.

A bad room-correction system does the opposite. If it fails to correctly determine your speaker configuration, for example, it can make voices sound boomy or thin, or create distortion that makes the system sound harsh. If the system’s designers ignored good audio science, it could end up producing a boring, dull sound—or an unnaturally glaring sound.

How does room correction work?

Room-correction systems employ what’s known as a “target curve,” a certain balance of sound frequencies they’re trying to achieve when you’re sitting in your favorite listening chair. First, the system runs measurements to find out how a room—and the positioning of the speakers and listening chairs within that room—is affecting the sound, and then it figures out how it can adjust the sound to hit that target curve.

With receivers, the process starts with your placing a test microphone (like the one shown in the photo at the top, usually included with the receiver) in the place where you normally sit. The receiver then plays test tones through the speakers, analyzes the sound picked up by the microphone to figure out what effect the room acoustics are having, and then equalizes the level and timing of the different frequency ranges of sound to even everything out. This process also has the ability to correct any flaws in the speakers (boomy bass, for example), as well as to set the appropriate delay time for each speaker so that sounds from all of them arrive at your ears simultaneously and to adjust the volume level of the speakers so that the sound is balanced all around the room.

In wireless speakers, the process is similar, except the microphone may be built into the speaker or the system may use your smartphone’s microphone.

Some room-correction systems let you run these tests in multiple seating positions, which improves the accuracy of the system and also lets it produce good sound for everyone in the room rather than for just one listener. And some receivers let you further tweak the sound through a smartphone app or the receiver’s on-screen menu.

Different systems use different target curves, chosen by the engineers at the company that created the room-correction technology. But they haven’t always chosen wisely, which should come as no surprise because even audio researchers sometimes disagree on this topic.

Furthermore, the systems sometimes lack the computing power to make an accurate assessment of the configuration of a speaker system and a room’s acoustics, and/or they lack the audio processing power to make all the needed adjustments. Poorly designed systems often miscalculate the bass capabilities of a speaker and the distance from the microphone to the speaker, resulting in inappropriate subwoofer crossover settings, which can make voices sound boomy or thin, and inaccurate speaker delay settings, which can ruin the sense of envelopment that a good surround-sound system produces.

As a result, whereas some room-correction systems we’ve used have made the sound much better, some have made our audio gear sound worse.

The big names in room correction

The best-known room-correction technology is Audyssey MultEQ; it’s available for any manufacturer to license and is most prominently used in Denon and Marantz receivers. You can find three variants—MultEQ, MultEQ XT, and MultEQ XT32—which differ mostly in the increasing precision of the corrections they make. All versions of MultEQ can correct the sound for multiple seating positions: six positions for MultEQ and eight for MultEQ XT and MultEQ XT32. MultEQ XT32 also allows a receiver to create independent equalization for two subwoofers, which should provide smooth bass response over a large portion of a living room—something a single subwoofer can’t do. Denon and Marantz also offer the $20 Audyssey MultEQ Editor app for iOS and Android, which allows manual adjustment of a variety of sound parameters.

Other AV receivers use proprietary technologies developed in-house by the manufacturer: Onkyo’s AccuEQ, Pioneer’s Multi-Channel Acoustic Calibration (MCACC), Sony’s Digital Cinema Auto Calibration (DCAC) EX, and Yamaha’s Parametric Room Optimizer (YPAO). Like Audyssey’s technology, some of these have multiple versions with different capabilities. For example, Pioneer offers basic MCACC, Advanced MCACC, and MCACC Pro, while Yamaha offers standard YPAO and YPAO R.S.C., which itself comes in two variants.

A few companies specialize in very powerful room-correction technologies intended more for high-end audio devices. Dirac Live is a licensed technology found in audio components from Arcam, Emotiva, NAD, and others, and also in standalone audio processors from miniDSP, such as the DDRC-24, which starts at $450. Anthem Room Correction is found in Anthem stereo components and surround processors, as well as in a few soundbars, wireless speakers, and amplifiers from MartinLogan and Paradigm. Trinnov Optimizer is used in Trinnov components and in the JBL Synthesis SDP-75 surround-sound processor.

Many subwoofers have room correction built in. This is a good idea, at least in theory, because the most severe effects of room acoustics occur in the bass frequencies. For example, most MartinLogan and Paradigm subs include Anthem Room Correction, and many ELAC subwoofers offer room correction through the ELAC SUB Control app for iOS and Android. In both cases, the control app calculates the equalization function using the microphone in the smartphone or tablet to do the measurements. (MartinLogan and Paradigm subs can use an optional $120 microphone kit for more accurate measurements.) Some other subwoofers offer similarly advanced systems, while some use simpler, more generic room-correction systems.

Room correction has just started to make its way into wireless speakers. Sonos’s Play:5, a pick in our best multiroom wireless speaker system guide, performs room correction through the Sonos Trueplay app and the microphone built into your smartphone. Some wireless speakers, such as the Amazon Echo Studio and the UE Hyperboom (which we’re currently evaluating for the next update of our best portable Bluetooth speaker guide), have an automatic room-correction function that uses a built-in microphone to continuously monitor the sound and optimize it for wherever the speaker is placed.

Which room-correction systems work the best?

Although I’ve used many room-correction systems and have my opinion on how well each one works, I wanted to get additional opinions, so I asked Wirecutter senior staff writer Chris Heinonen and contributing writer Dennis Burger to weigh in. Both are enthusiastic about room correction, but both also have reservations about some of the systems currently available.

Chris and Dennis both recommend MultEQ XT and XT32 strongly, especially in conjunction with the MultEQ Editor app. In Dennis’s experience testing receivers, he has found that the standard version of MultEQ doesn’t have enough power to deliver optimum results consistently.

It’s hard to generalize about the brand-exclusive technologies found in many receivers because they come in so many variants, but both Chris and Dennis have found that only the version of Yamaha’s YPAO R.S.C. that allows measurements from multiple seating positions can be expected to deliver an improvement in sound quality most of the time. They also like the higher-end Dirac, Anthem, and Trinnov systems, but those are generally available only in high-priced electronics, and the Dirac and Trinnov technologies can be complex to set up.

In subwoofers, I’ve found that the app-based Anthem and ELAC systems work quite well, and I’ve had good experiences with similar systems. But none of the simpler, more generic systems I’ve tested have been worth fooling with; most of them barely even had a measurable effect, much less an audible one, in my tests. However, if your receiver has a good room-correction system, you don’t need another one in your subwoofer. Also consider: For manufacturers, adding room correction either increases the cost of a subwoofer or requires downgrading something else in the subwoofer to keep the price down—maybe just the exterior finish, but possibly also the woofer driver or the amplifier. So you might get better sound for the same money with a sub that doesn’t offer room correction.

For Dennis, what divides the best of these systems from the also-rans is the ability to confine room correction to lower frequencies, below about 300 Hz (slightly below the frequency of the highest string on a guitar). Many experts believe that because the human ear adjusts to different acoustical environments—your friend’s voice doesn’t suddenly sound different when you both walk outside, for example—trying to correct for room acoustics at midrange and treble frequencies can make the resulting sound less natural. However, because room acoustics can cause such large variations in bass reproduction, experts believe that room correction is necessary at these low frequencies.

Still, the end result depends on your speakers and your room. If your speakers and/or your room have a lot of sonic flaws, a good room-correction system will almost certainly help. If you have well-engineered speakers and a subwoofer or two, properly placed in a rectangular residential living room, you may find that room correction makes only subtle improvements—and in a few cases, it might make the sound worse.

While scientists and engineers can debate the merits of different target curves, ultimately only you can decide if you like the effects of room correction on your audio system. Since the technology is built into most AV receivers these days, you can easily hear the effect for yourself—and if you don’t like it, you can always turn it off.