You were probably introduced to the aural heaven of surround sound—like I was—when movie theaters began adding speakers along the sides of their auditoriums. I remember my first surround-sound experience, watching The Empire Strikes Back in a crowded theater in Hollywood, amazed by the vivid sense of envelopment. I even found myself glancing around in the darkness, trying to understand how the movie had suddenly immersed me in its fantasy. However it was happening, it was a transcendent bliss that made me forget about my popcorn, my friends in the seats next to me, even my life outside the auditorium. I was in the film!

For years, it was only inside movie theaters that I could achieve such spiritual satisfaction. At home, I had to make do—slumped shoulders and all—with our family TV’s mono speaker and later two-channel stereo, which was splendid at the time but came nowhere near duplicating the bliss of the darkened, speaker-studded theater. Until the late 1990s, the popular medium for movies was VHS, a woefully inadequate platform for video and especially sound. Laserdiscs, primarily a videophile niche format, provided far better potential for video quality and also boasted sufficient space to adequately present the film’s soundtrack, but the unwieldy and expensive nature of laserdiscs never appealed to me. I shouldn’t have to flip discs as many as eight times to enjoy my favorite films.

With the advent of the hugely popular DVD format—your favorite movies on (usually) one-sided discs the size of CDs!—we’re getting a whole new dimension of sound. In fact, we’re getting several dimensions. When you’re shopping for home-theater receivers and speaker packages, you might be at a loss for what technologies you need to play movies, listen to music, and play games to their full aural advantage. Let’s take a look at the different kinds of sound you can conjure in your home theater.

Home Theater Surround Sound
Today, it’s more and more possible to equate—and even surpass—the quality of movie-theater surround sound in your home theater or living room. Most films today are produced in multichannel sound, and DVDs faithfully reproduce that barrage of sound. The typical home-theater setup contains 5.1 channels, which means that your audio source (be it your DVD player, game console, or high-end audio player) is sending six separate tracks of sound to your speakers—left front, right front, center, left rear, right rear, and the all-important “.1” subwoofer, which is responsible for the deep bass.

Most of today's DVDs are encoded with a surround track that conforms to this 5.1 speaker setup. However, adding to your confusion is an array of other available sound options, such as 2.0, 4.0, 6.1, and 7.1 technologies. Growing increasingly—but gradually—more popular are the latter formats, which send sound information to new places around the room. For example, 6.1 and 7.1 add discrete channels of sound behind your head. In the DVD market, if you take a close look, you’ll find technologies conforming to these sound options, such as Dolby Surround, Dolby Pro-Logic, Dolby Digital 5.1, Dolby Digital EX, DTS 5.1, and DTS-ES 6.1. In addition, an increasing number of music CDs—in glorious Super Audio CD (SACD), DVD-Audio (DVD-A), and DTS-ES 6.1—are finding their way into homes. Even game consoles such as the Sony PlayStation and the Microsoft Xbox can present most games in multichannel sound. And forthcoming HDTV broadcasts will surely feature surround sound. Thanks mostly to the incredible surge in DVD popularity over the past 5 years, multichannel sound is now the way we prefer the majority of our entertainment.

But what do all these sound options mean? Do you need them all? Can you get away with just one and ignore the rest? The short answer to that question is no, and the longer answer begins with another question: Why would you want to? The plethora of sound options available for your connected home make for a divine foundation from which to begin any search for inner peace and Taoist balance. Let’s take a look at what’s out there—the different sound technologies that you can implement in your home theater to attain aural nirvana.

Stereo
Of course, it all begins with stereo (a left channel and a right channel), which some consider to be the purest form of audio reproduction. We each have two ears, right? Stereo is the most accurate translation of any perceived sound for the simple reason that it’s the closest to human physiology. Even today, most audio components ship with a cheap pair of RCA-style audio cables for stereo connections—even though the components are generally capable of so much more.

CDs, VHS tapes, and even most DVDs are encoded with stereo tracks, and we’ve been happy with stereo sound for years. It’s natural. It sounds good. But to get the most out of today’s multichannel enticements, you’ll really need to get past the notion of the superiority of stereo. Multichannel technology doesn’t necessarily pretend to offer realism in movie soundtracks or music—it wants to wow you. It wants to reach into your pleasure center and open up new realms of sound appreciation.

Dolby Surround
Dolby Laboratories has always been a surround-sound pioneer. The company’s first surround effort was Dolby Surround, a three-channel technology that sent discrete sound information to the left and right speakers, as with a stereo setup, but added a mono rear channel whose information was split into two speakers at the back of the room. The mono surround tracks were limited in their frequency, so the experience typically amounted to mere ambience, but it was the first real step toward the surround sound we know today.

Dolby Pro Logic II and IIx
You probably have quite a few DVDs labeled Dolby Surround, but in truth, they’re four-channel Dolby Pro Logic discs. The next step above Dolby Surround, the Dolby Pro Logic technology sends discrete information to the front left, front right, center rear—and a new center channel. An essential innovation in the evolution of home-theater sound, the center channel takes care of a lot of sound at the center of the screen, and not just dialog.

The innovation of Dolby Pro Logic is that the four channels occupy only two audio tracks. Dolby decoders use a technique called matrixing to pull four channels of information from essentially a stereo signal. Of course, this is a perfect design for components (e.g., most VCRs) that are capable of outputting only two audio channels. Magically, Dolby Pro Logic conceals the channels inside that stereo track, indicating which sounds should come from the left, right, center, and rear speakers. You’ll find that many VHS tapes and even some DVDs are encoded with Dolby Pro Logic on their stereo tracks to create an immersive surround experience.

Dolby’s recently unveiled Dolby Pro Logic IIx format extends the functionality of Dolby Pro Logic II by expanding all two-channel and 5.1-channel information for playback in 6.1 and 7.1 environments. The result is an even more seamless, wraparound sound field that doesn't require specially encoded program content.

Dolby Digital
Dolby Digital (aka AC-3) is the market's surround-sound standard for films, providing heavenly multichannel sound for movie theaters and DVDs. Dolby Digital significantly upgrades Dolby Pro Logic by offering six discrete channels of sound for use in not only DVDs but also games, HDTV broadcasts, and high-end music CDs. The more capable your system, and the more speakers you have surrounding you, the more profound your experience of multichannel bliss will be.

Dolby Digital 5.1
Six-channel Dolby Digital surround sound is designated 5.1—five full-frequency channels and one for the subwoofer’s low-frequency effects (LFE). The specific wonder of Dolby Digital 5.1 is that it sends discrete signals to the left-rear and right-rear channels. The availability of independent sound channels in the rear—essentially an entirely new stereo track intended solely for surround effects—transforms films into a truly enveloping aural experience.

Dolby Digital 5.1, combined with the soaring popularity of the DVD, has changed the way we enjoy entertainment. The two technologies, taken together, deliver far higher sound quality than we’ve ever known in the home. A case could be made that it's because of this loving marriage of technologies that surround sound has blasted off for so many forms of entertainment. Take gaming, for example: Gone are the days of lifeless (mono) Nintendo. You can now enjoy true surround-sound first-person shooters, in which you are the character, in the game, with danger coming from all directions. And if it weren't for the popularity of Dolby Digital 5.1, we wouldn't be enjoying the benefits of today's increasingly fascinating audio innovations.

Dolby Digital EX
As much as you might have despised Jar Jar Binks and perhaps the rest of Star Wars: Episode One: The Phantom Menace, the debut of that film introduced the next stage in the evolution of Dolby Digital. Dolby Digital EX improves on Dolby Digital 5.1 by adding a center-back channel between the existing left and right rear channels—essentially, directly behind your head. This channel is a matrixed channel that derives its information from the existing left-rear and right-rear channels. If you have the right setup—and you will need a capable Dolby Digital receiver to realize the full potential of EX, as well as EX-encoded discs, which are still relatively rare—you will melt liquidly into your sofa or easy chair in a puddle of audio ecstasy as those rear-channel effects swirl around you.

DTS
A relatively recent Dolby competitor, Digital Theater Systems (DTS) offers another common digital-sound option. DTS debuted in theaters in 1993, on the occasion of Steven Spielberg’s groundbreaking Jurassic Park. DTS-encoded DVDs require a special DTS decoder that's separate from a Dolby Digital decoder. Most of DVD players currently on the market offer a DTS output, and most new home-theater processors or receivers offer both Dolby Digital and DTS decoding.

DTS Neo:6
DTS Neo:6, DTS's answer to Dolby's Pro Logic technologies, provides as many as six full-band channels of matrix decoding from stereo matrix material. If you have a 5.1 or 6.1 setup, you can enjoy surround presentations from matrixed 2.0 material on VHS tapes, DVDs, and so on. DTS Neo:6 can also generate a center-back channel from DTS 5.1 material. Of course, a DTS Neo:6 presentation won't match the clarity and specificity of a discrete-channel track, but it provides a nice sense of ambience nevertheless.

DTS 5.1
DTS 5.1 is a six-channel surround-sound technology that has become as popular—if not more so—than Dolby Digital 5.1. The DTS technology typically uses less compression than Dolby Digital does, and it offers a higher data rate. Given those facts, most people automatically maintain that it sounds better than Dolby Digital. But the situation is a bit more complicated than that. Dolby uses a technology called perceptual encoding to optimize its compression, so, for example, side-by-side comparisons of DVDs encoded with both formats often lead to inconclusive results. Sometimes, the sound quality is so similar that you wonder why the authors of the disc bothered to waste space with both formats.

DTS-Extended Surround (ES) 6.1
Upping the ante in the war for the center-back channel (that bliss blaster that's pointed at the back of your head), DTS-ES is the only format currently on the market that's capable of delivering 6.1 channels of discrete audio. No matrixed channel here, as with Dolby Digital EX—that back channel gets its own information, specifically intended to blow your ears away. But fear not: If you don't happen to have a speaker behind your head, DTS-ES–encoded soundtracks are fully compatible with existing DTS 5.1 decoders. If you do have that speaker (or, better, if you've split the channel into two back-center speakers), the DTS-ES 6.1 decoder will play that discrete channel and subtract the matrixed information from the left and right surround channels. And, yes, you will have achieved nirvana.

Unfortunately, the number of DTS-ES 6.1-encoded DVDs and music DVDs is relatively small. The format hasn't caught on in a big way, simply because consumers haven't really taken to the notion of additional speakers beyond the basic 5.1 setup.

THX
Contrary to popular belief, THX isn't a technology in the realm of Dolby and DTS. Rather, it is an audio stamp of approval. When you see the THX logo on a particular piece of hardware (e.g., home-theater receiver, DVD player) or entertainment (e.g., film, TV, DVD, game, music), you know that the item has endured a rigorous THX quality-assurance test. The benefit of such a stamp of approval is that participants on both sides of the equation—from sound engineers to filmmakers to exhibitors to DVD authors to the consumer—know that a given product will deliver a terrific entertainment experience.

Through an array of peerless quality-assurance standards, technologies, and certification programs, THX—a third-party entity—monitors both visual and audio content from content creation through presentation. When George Lucas founded THX in the early 1980s, he said, “Sound is 50 percent of the motion picture experience,” then complained that most theatres were failing to deliver a sound presentation that matched the filmmaker’s artistic vision. It was Lucas who believed that the cinema industry could benefit from a quality control standard to deliver a consistent level of performance, across all theatre venues. THX has since expanded beyond the box office—the company now bestows its stamp of approval on other entertainment media and presentation venues in which picture and sound are crucial elements.

Sounds of the Future
So what kind of bliss might our ears be experiencing over the coming months and years? What will the evolution of home-theater audio lead to? One potential presence in the arena of home-theater audio is Sony's proprietary eight-channel Sony Dynamic Digital Sound (SDDS) technology, which you might have experienced in theaters. It adds left-center and right-center channels to the typical 5.1 setup. Some home-theater receivers and DVD players are capable of decoding SDDS, but in general the format has seen only limited, proprietary use.

If you're into music, and you're shopping for a DVD player, you might want to consider DVD-A and SACD—high-end music formats that are just now appearing together on players after a few years of competition. Hybrid players are becoming quite reasonable, but only the better (i.e., more expensive) players offer precise bass-management capabilities. Audiophiles will find these still-relatively-niche technologies—which offer extremely high fidelity and dreamy multichannel mixes—spectacular.

A new Dolby technology just catching on is Dolby Headphone, an algorithm that somehow reproduces the dynamics of a 5.1-channel surround-sound experience and wraps it around your head in two speakers. You can use any pair of stereo headphones to enjoy a greater sense of immersion—for example, if it's late at night and you don't want your pounding subwoofer to wake the kids.

Rumors fly in the audio realm of as many as 10.1 channels describing the future of the home theater, speaker configurations that surround you so completely with high-fidelity sound that you’re reduced to a quivering blob of wet ecstasy in your seat. Whatever the future holds, we’re drooling for it.