|Tomlinson Holman’s Latest Experiment|
|Home Theater Feature Articles Audio Related Articles|
|Written by Kim Wilson|
|Thursday, 13 December 2007|
Tomlinson Holman’s Latest Experiment
A young woman approaches the tall, sandy-haired gentleman in the unassuming and uncorporate-like Polo shirt and khaki pants. She shakes his hand and expresses her genuine appreciation: "Thank you so much for THX. When my friends and I go the movies, we always look for the THX logo to ensure we’re getting the best sound."
Returning her praise with a smile, Tomlinson Holman, the creator of Lucasfilm’s THX technology, remarks he’s pleased she’s received so much enjoyment.
Short for Tomlinson Holman’s eXperiment, THX certified products are the backbone of some of the best professional and residential theater systems. Not satisfied to leave his legacy there, Tom Holman, co-founder of TMH Corporation, is conducting a new experiment, which he discussed during the DSP World Conference in San Jose last April.
Led into a pitch-black room, I am carefully guided to a chair, ostensibly the venue’s sweet-spot. Except for the murmuring of conventioneers walking the aisles, I sit in complete silence and darkness waiting in anticipation for what I hope will be sonic nirvana.
A preamble explaining the process and some basic attributes of the system seem to come from a live speaker in the middle of the room. Then a ping-pong ball starts to bounce around the room. Instead of detecting actual speaker locations, it is as if I am wearing headphones and listening to a binaural recording. While this has sort of an "in your head" effect, the spatial cues indicate a much wider environment. There is no semblance of sounds jumping from one location to another. Transitions are smooth and absolutely natural, including the sensations of height and depth.
All of a sudden, some union goon is dropping planks just outside the booth. Hey be quiet out there, there’s a demonstration going on in here. Wait a minute, I’m no longer sitting in a tiny cubicle. I’ve been transported to an empty concert hall and someone is barking out orders to the crew that is setting up for a show. The piano is being tuned and several folks are talking in hushed tones, but the highly ambient acoustics allow the sounds to travel way out here, to the center of the hall.
We are transitioned to a concert in progress, playing Samuel Barber’s "Essay for Orchestra." The thundering kettle drums couldn’t sound more real if they were in the room with me and it doesn’t take much suspension of disbelief to accept that they are right on stage, about 50 to 100 feet in front of me. This segues into the final demonstration piece, a choir and orchestra concluding a rousing and emotionally moving rendition of Handel’s triumphant "Hallelujah Chorus" from "The Messiah." The deafening roar of the audience is chilling. I sense the movement of people in my row and the applause coming from the balcony and box seats in the upper portion of the theater. Due to the "high" position speakers, vertical reflection cues are far more present. When the conductor returns to the stage for his final bow, the overwhelming response from the audience rises from the right side of the theater and sweeps across the room in a giant wave of sound.
What I have just experienced is a 10.2 sound system, consisting of 10 speaker locations and 2 LFE (low frequency effect) tracks. The term "breathtaking" hardly conveys the level of realism this demonstration delivers. This is as close to live as I’ve ever heard from a reproduced sound source. Yes, the instruments sound wonderful, natural and pure, but it is the perfect and accurate simulation of acoustics and ambience that convinces your mind that you are in a completely different environment.
Just like a theatrical or residential theater, the speaker array consists of front left, right and center speakers. An additional pair of front speakers is placed in the "wide" position on either side of the left and right speakers at a 60-degree angle to the listening position for creation of the ultra-spacious soundfield. To provide a sense of height and to reproduce front-firing ambient effects, two speakers are hung from the ceiling in the "high" position. They are placed equidistant between the left and right speakers, at an angle of 30 degrees, and the "wide" speakers, at 45 degrees. Speakers are placed in the surround left and right position at 110 degrees and a center surround speaker is located 180 degrees from the front center speaker.
More speakers are placed in front of the listener (high and wide positions) because we have better localization in front of us, rather than behind us. In the traditional surround position there are two speakers, one a dipole and one direct radiating. Having both types of surround speakers ensures the correct dispersion for all possible sound sources. The type of material reproduced dictates which speaker delivers audio.
The system consists of ten Genelec self-powered speakers. Rated at a maximum output of 121dB down to 24Hz, Australian-made Whise subwoofers, driven by a QSC amplifier (250 wpc), have the task of delivering the increased bandwidth of two LFE tracks. A subwoofer is located on either side of the listening area, handling bass for all the speakers on that side of the room. An Adcom 7500 amp is used to drive the M & K dipole speakers. Three proprietary DTS decoders are wired in parallel to deliver the multi-channel source material. Seven Rane GE60 equalizers are incorporated for room equalization.
The Bit Rate of Reality
TMH has chosen the DSP World Conference as a venue for the first public demonstration of this system because if there is ever going to be a pipeline to the consumer for 10-channel sound, it will be the responsibility of DSP engineers to find a method of delivery.
What is the bit rate of reality? Will 96kHz/24bit DVD –Audio answer the age-old desire to record and reproduce sound with enough realism to make you believe you are actually listening to live music?
DVD-Audio does address the need for higher bit rates and these greater word lengths will ultimately realize good 128dB dynamic range material with dither, which is necessary to eliminate distortion.
Other than sample rate and word length, spatial positioning is a key factor in perceptual realism. Using human hearing as the design goal, Holman feels the natural progression toward a higher level of reality is more channels, rather than additional sampling rates or word length. Even the extra matrixed surround channel found in the latest theatrical soundtracks (see last month’s article on the new sound system for ‘Star Wars: Episode 1 – The Phantom Menace’) represents limited thinking, according to Holman.
Delivering 10.2 audio is a lot more than just adding speakers and components. Since there is no such source material commercially available, the demonstration material had to be developed from scratch. Creating 10.2 samples was challenging, as post-production facilities and recording studios are only equipped with 5.1 capabilities.
True, it may be a long time before such a system ever becomes commercially viable, even in movie theaters, because it would require new methods of mixing and delivering the extra channels. Even with all the obstacles such a system would generate, there has been interest from a few high-end installers, who plan to provide this 10.2 demonstration, with the assistance of TMH. The cost and maintenance of the system prevents permanent displays, but customers will have a brief opportunity to hear the (possible) future of multi-channel sound.
If at some point 10-channel audio becomes available via some form of DSP, it may be as a virtual mode, emulating the effect of all those speakers. Even if it’s not quite as good as the real thing, it just might blow away 5.1 audio as we know it. There is no way to know how Holman’s latest experiment may or may not proceed. However, his continuing and diligent pursuit for the ultimate sound experience has made me realize that we haven’t reached the end of the journey. In fact, we’ve only just begun.