Home audio technology has advanced at a dizzying pace in recent years, with home theater and surround-sound systems offering more channels, enhanced channel separation, and improved frequency response and reproduction. These advancements present great opportunities for A/V integrators, as homeowners who demand the best of the best may be willing to invest more. It also presents challenges, however, because these clients expect their installation professionals to deliver an undeniably great aural experience, regardless of uncontrollable factors like the shape, size and contents of the room. That’s where room correction comes in.
Every detail of a room affects how a listener perceives audio played in that room. That means every piece of furniture, every lamp, every wall decoration and every window has the potential to diminish the listening experience.
Traditionally, integrators might painstakingly test different speaker placements and basic integrated room correction, but that often delivers middling results and is not ideal for systems specifying in-ceiling or in-wall speakers. Luckily, there has been another wave of innovative products that help every system, no matter the size or sophistication, reach its maximum potential: standalone room correction technologies.
Talk to any audio professional and they will tell you this is the truth. Even professional mastering studios that spend hundreds of thousands of dollars on damping products employ room correction technology to ensure the best possible results. Very few homeowners are willing to spend a ton of extra money on professional damping, and that’s where advanced room correction technologies really prove their worth.
For a few hundred dollars, today’s best room correction products can compensate for the acoustic characteristics and abnormalities of any room using sophisticated algorithms and testing. The trick is finding the best solution, and not falling prey to cheaper, less-advanced options that have become standard and generally accepted by end-users in many home theater receivers. It’s the classic case of people not knowing what their missing, simply because they have not been shown the light.
What Is Room Correction?
So what does room correction technology actually do? In the simplest terms, the most common room correction technologies use microphones and test signals to measure the magnitude response, or perceived volume, in a room, and then automatically adjust the system’s output to optimize the sound for a single, specific area where the microphone was placed. Newer, more advanced options follow this step with a minimum phase response correction to equalize the signal.
Phase response is how an audio system presents the timing of audio from one speaker to the next, based on how our ears perceive sound due to tiny variations in timing created by different sound reflecting surfaces. That’s why listeners spread throughout a room may each hear slightly different timings, especially near corners. Audio receivers typically do not include phase response correction, and thus are only capable of improving the sound for one specific spot. This presents a problem, because what is a room correction system worth if it only sounds great for one listener?
In truth, it’s not worth a whole lot. But as I mentioned above, the best standalone room correction solutions use advanced algorithms to measure and adjust the full characteristics of a sound system, including both phase response and magnitude response. The result is an amazing ability to improve spatial robustness — the area in which optimal sound is heard. If you doubt it is truly “amazing,” know that until they heard it for themselves, BMW engineers didn’t believe this level of audio processing was possible, and then decided to implement it in some vehicles after being proven wrong.
Integrators can explain this advanced capability to homeowners as a “smart” audio processing solution — one that precisely measures all the acoustic characteristics of a room and automatically adjusts its processing based on the test results. Especially for younger clients who are more likely to purchase and be familiar with smart home technologies, presenting room correction as a “smart” technology could be a powerful selling tool.
Basic Room EQ Can Over-Process Audio
In contrast, the more basic, less-smart technologies often run into problems with over-processing, which can end up degrading the listening experience instead of improving it, especially if they employ a less sophisticated method of phase response correction. This happens when too much digital filtering is applied, and can result in a less natural sounding system where individual notes may not occur at precisely the right time and effectively change the audio.
As for setup procedure, simpler receiver-based room testing often requires just a few on-screen steps that quickly adjust some basic processing, while setup for the best products entails much more input and can effectively eliminate any phase issues, which most noticeably affects the perceived timing of individual notes in music.
This is achieved in part by utilizing computer-based software that is much more powerful than integrated receiver correction. It may sound complex, but the setup process is straightforward and can end up saving integrators time and money because it is advanced enough to get the audio right the first time.
Much of this has to do with how humans perceive sound, based on the minute differences in timing created by the various sound-reflecting surfaces in a room. It took decades of research and development for this level of technology to become what it is today, and many of the early attempts were either partially successful or even detrimental to accurate reproduction and listener reception.
While it’s probably not necessary to explain all of this to every client, it is important that integrators understand how the different technologies function and produce varying results. Just as it’s crucial to know the latest and greatest audio components and speakers, being able to deliver the highest-quality room correction can be a powerful selling tool for an integrator’s arsenal. This would be especially easy to show for any companies with a showroom, where an A/B test can reveal stark differences to clients.
All in all, the more complex the surround system is, and the larger or more crowded a room is, the more need there is for high quality room correction.
Considering the relatively low cost-to-benefit ratio of these technologies, it serves integrators to learn about the latest products and advancements and specify them to any clients looking for the absolute best audio experience possible today.
Niklas Thorin is general manager, high performance at Dirac Research AB.
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