by Ron Goldberg
What if getting dramatically improved sonics had less to do with home theater or home stereo gear and more to do with the environment you listen in? It’s often true — when it comes to audio, there’s a 600 lb. gorilla in your room, and it’s the room itself. Room correction may be in order.
Room Correction: What Is It?
Every listening room has a sound of its own. Natural acoustics, affected by room shape, material, furniture and other factors make some frequencies louder and more resonant—or softer and less audible—than others. The effect can change depending on where you sit, where you place speakers, and other variables. Room correction is a digital signal processing feature in receivers and preamps that performs intelligent equalization of audio signals, based on the characteristics of the room itself, and even where you sit in it.
Many of these variables can’t be practically changed, like the shape of the room or the height of the ceiling. Subtle fixes, like slight movements in speaker placement and a few strategic rugs to soften sonic reflections can make a noticeable improvement in your sound. But room correction can make a night and day difference.
How To Do It
Components that employ room correction come with a small microphone that gets plugged into the front of the receiver or preamp. You place the mic at your typical seating area and start the process in the setup menu.
A series of test tone sweeps then gets played through each speaker, and the microphone picks them up. When the tones are finished, the gear does some swift calculations and bingo—you get customized equalization that’s specific to your room, and even to your actual listening position. Better room correction systems can even make multiple readings and optimizations for more than one seating location. So if you sit on the sofa but the kids or your friends sit off to the side, the room corrections can take these into account and make intelligent compromises.
Room correction used to be extremely esoteric technology, but now you see it offered in many forms, from entry-level receivers to high-end outboard units you connect to a system of audio separates. The differences between them lie in the sophistication of the treatments, such as how many ‘bands’ of equalization, how many listening points it will compensate for, and how well it works with frequencies below 200 Hz, which are usually the troublemakers in your room. Some room correction components serve double duty as a preamp or outboard crossover.
Should You Do It? (Yes, Of Course!)
You can hire an acoustic professional too, who can make room readings for the offending frequencies, change or add materials on/in the walls, ceilings and/or floors, and make your room (much) better sounding through physical means (Read about Easy Home Theater Audio Tweaks here.). Or you can push a button on your gear and get a convincing version of those benefits in about 2 minutes, with no additional cost. [Ideally, you should do both, but rarely are we permitted to do the ideal thing. Ed.]
If your gear has a room correction feature and you haven’t set it up yet, you really ought to and will be happy you did. Here are a few tips for getting the best results:
• When you place the microphone, don’t just stick it on the couch, you’ll get a poor reading. Be sure the mic is placed where your ears would be; use a pile of books or such to elevate it.
• Be sure it’s quiet when you perform the process; the mike hears everything. Cars driving down your block and the dog barking down the street will affect the reading. Run the dishwasher later.
• If you must correct for multiple seating positions, understand that you’re making compromises to all of them. You’ll have better results correcting for the main seating area. Ask your guests to forgive the uneven frequency peaks at their seats when you invite them for a movie. [Ideally, you want every seat in the room to have the same audio experience, but sometimes this isn’t possible. Ed.]
• Do an A-B test after the correction; listen with the correction and without. It will sound like your gear just got home from a 6-month bodybuilding course.
Room correction can’t perform miracles, but you can help it get the best results. Speakers often depend on specific placements to sound their best (distance to walls, toe-in, etc.). Follow the speaker’s recommended placement instructions as best you can for your room. After you’ve done that, do the room correction.
Then sit back and enjoy what your system is really supposed to sound like.
Chicken or Egg: Planning a Home Theater with THX
Sound Setups: Three Great Audiophile Rooms
This article was originally published on February 2, 2015 and was updated on September 25, 2015.