The S&V Interview

S&V: To give readers a sense of the breadth of what Audyssey has to offer, can you provide a brief overview of the key Audyssey technologies in use today?
Clark: Sure, let’s run through them…

SubEQ HT was the first technology in the home theater space designed to optimize multiple subwoofers. It performs time and level alignment and then treats multiple subwoofers as a single unit for EQ purposes. This is important because, ultimately, the subwoofers work off a single mono signal.

Dynamic EQ corrects for what was long understood in psychoacoustics as a human hearing “problem.” The perceived tonal balance of the sound changes when the volume changes. Dynamic EQ compensates not just for the master volume setting, but also the variable level of the content by applying what is often referred to the Fletcher-Munson curve or an equal-loudness contour.

Dynamic Volume is based on research performed at USC that tracked how people actively adjust volume when watching films at home. The research found that viewers tend to increase volume to keep quiet passages from being too quiet and reduce volume to keep loud passages from being too loud. Dynamic Volume brings hands-free listening. It’s also great for taming obnoxious advertisements.

DSX looks for width and height cues present in multichannel soundtracks and directs them to “Wide” speakers to create a more immersive experience. It was the first technology to get one critical thing right: Human auditory acuity is greatest in the forward, horizontal plane. That is, we localize left-to-right in front of us the best. We continue to get positive feedback on how well DSX Wide speakers expand the sound field. Unfortunately, DSX has been largely superseded by Dolby Atmos, DTS:X, and other object-based formats that support multiple speakers.

S&V: Let’s talk for a moment about the state of the art at Audyssey, particularly the evolution to the highly refined MultEQ XT32 system.
Clark: MultEQ XT32 is based on a patented method of reallocating the FIR filtering power from high frequencies toward the low frequencies. An FIR is based on “taps” or “coefficients.” These are computationally intensive to calculate on a real-time input signal, especially in modern systems that might have 13 or more channels. XT32 splits the filtering into bands without introducing phase artifacts, aside from the minimal, sub-audible phase adjustments required to achieve the desired EQ response.

As a result, the XT32 FIR system is effectively 32 times more efficient — that is, the taps we run are 32 times more effective than they would be without XT32. That gives XT32 note-by-note (half step, 12 per octave) correcting power or better from 50Hz up. It also has whole-step control down to 25Hz, which means the notes G0 (24.5Hz) and A0 (27.5Hz — lowest note on a piano and lower than the lowest note in a typical orchestra, except for one with a pipe organ) can be separately EQ’d. Even the XT level of MultEQ now benefits from the same technology, enabling less expensive DSP systems to have correcting power that was previously available only in top-of-the-line systems.

S&V: There was a time when Audyssey was the only game in town but today there is quite a bit of competition. What makes Audyssey stand apart from other automated room-correction systems?
Clark: Audyssey starts with great measurements. The repeated chirp measurements we use are the most precise measurement method we’ve seen. The system is noise-canceling (unlike pink noise or single-sweep measurements) and provides an impulse response (system response with time and frequency components), which enables precise trim and distance calculations — we can even detect incorrect polarity (wiring faults) in most cases.

MultEQ can be distilled to three fundamentals:
1. Multiple position measurement, including a method to combine those measurements that matches psychoacoustic perception.
2. A target curve (the resulting frequency response the EQ is calculated to achieve) based on science and industry experience.
3. FIR filters.

The Audyssey target curve is based on our experience measuring many different home theater rooms, and has been validated by data from professional installers who use MultEQ — data representing tens of thousands of measurements in thousands of rooms. Moreover, this data has led to other discoveries — including the finding that full-range EQ is a valuable tool for dialing in the last bit of speaker/channel matching.

Audyssey’s Midrange Compensation adjustment is an oft-misunderstood reduction in the midrange frequencies that improves clarity for the vast majority of speaker systems — the adjustment works because it compensates for the change in directivity between a tweeter and midrange driver. With MultEQ-X, users can use Midrange Compensation on any of their EQ presets, or design their own.

FIR filters are used exclusively throughout the Audyssey MultEQ range, with the pinnacle being XT32. Because of their higher resolution and minimal impact on phase, FIR filters do the best job of improving in-room impulse response. As I mentioned earlier, XT32 is a proprietary technology that only Audyssey has. We can put more effective processing on a DSP than anyone else. A competitor would need 32 of the same processors to match the level of filtering provided by MultEQ-XT32, which occupies an entire DSP chip in an AVR.

Finally, Audyssey brings together much-needed companion technologies Dynamic EQ and Dynamic Volume. Where others rely on static target curves to achieve the correct balance of sound, Audyssey’s Dynamic EQ doesn’t need a bass boost in the target curve because it works to deliver the correct amounts of bass (and treble), regardless of the volume setting. And where other systems render the quietest passages inaudible when the volume is turned down, Dynamic Volume maintains all content at an audible level, even at lower-than-reference-volume settings.

S&V: If asked to sum up Audyssey’s legacy to date, what would you say? What’s the company’s greatest accomplishment?
Clark: Audyssey is driven to bring the best audio experiences to any environment or device. Throughout the history of the company, we’ve been proud to deliver technologies and products built around those technologies that are truly best in class. We’re as excited today as we were on Day One to keep innovating and moving audio technology forward.

In my opinion, the company’s greatest accomplishment is the MultEQ / Dynamic EQ / Dynamic Volume trifecta for optimizing the audio experience in any environment or on any device — be it with headphones, in a car or, notably, in a home cinema. I hope over time that MultEQ-X will take its place among those by being a platform that delivers our latest MultEQ innovations directly to customers.

S&V: What’s next for Audyssey and MultEQ-X?
Clark: We’re listening closely to early feedback and encouraging everyone to make their voices heard at Ask.Audyssey.com, our tech support ticketing system. We’re hard at work on Version 1.1, which will deliver customer-driven features, including target-curve EQ import. After that, we plan to implement some of the big ideas that we’ve had floating around in an effort to make MultEQ calibration even better. Users should expect regular updates and we’re excited to deliver them.

Meanwhile, we’re readying two hardware offerings that will give users even more precise measurements. The first is a special electronic adapter cable that will allow users of our Audyssey Pro Calibration Kit to use the kit with MultEQ-X and the latest AVRs; those users will also be able to extend the microphone cable up to 1 kilometer (3,281 feet). The second item is a more consumer-friendly — and lower-priced — calibrated microphone. We haven’t announced delivery dates yet, but registered MultEQ-X users — even those not yet licensed — will be notified by e-mail when these items are available.