Surround Sound: High Tech Meets the Beast Within Us

It's a tense moment during a suspense thriller. A cannibalistic serial killer has escaped from a maximum-security detention unit and eluded capture for long enough to work up a healthy appetite. Two small children are playing hide-and-seek in an overgrown lot behind their home.

They have forgotten mother's admonition to stay indoors, but we haven't. One is hiding in a dense shrub, holding his breath in case the other is nearby. It's dead—quiet except for some distant crows. Off-screen somewhere, and very near, a twig snaps, and we jump out of our seat. Then we hear "I see you!" and the adrenalin stops flowing—for the time being.

Long before movies, surround sound was saving our ancestors from saber-tooth tigers, giving them a second set of "eyes" with which they could not only watch their tails, but tell where any threat was coming from. Today, our ability to hear sounds coming from beside and behind us protects us from such contemporary hazards as approaching trucks and stalking hoodlums. Welcome to the world of surround sound!

Learning to listen to acoustical space is a normal part of growing up. By the time we are only a few months old we have already learned to discern the direction from which sounds are coming. Later, we take it for granted that every third-dimensional space has its own characteristic "surround sound." Only when that sound is unfamiliar or inappropriate or threatening do we think about it at all.

The Room Has a Voice of Its Own
Have you ever found yourself in a plush, upholstered room with heavy drapes, thick wall-to-wall carpeting, and lots of overstuffed furniture, and noticed how "funny" your voice sounds to you? That's because, when you're speaking indoors, you expeqt to hear the room you're in as well as the sound of your voice in it. When you don't "hear the room," you notice it.

In most enclosed spaces, we expect to hear sounds from two sources: directly, in a straight line from the source to our ears, and indirectly, a fraction of a second later, as reflections from the walls, floor, and ceiling. The reflections are usually much quieter than the direct sounds, but we are aware of them, even though we may not realize it. When they aren't there, we know it immediately. That's why your voice sounds unfamiliar in a very dead room. You hear it from your mouth and, by bone conduction, from your vocal cords. But you don't hear the room sound that usually accompanies it. Outdoors, we often hear reflections coming from nearby buildings. Think about the sound of footsteps in an alley between two buildings. In wide-open space, with nothing to bounce sounds back to us, our ears tell us we're in open space. There, all we hear are direct sounds, from birds, dogs, vehicles, and passing airplanes. The nature of the sonic space around us helps us orient ourselves to our environment. It's no wonder our senses rebel when halfofthat space is missing.

Sure, stereo through two channels is nice, and it can sound a lot more realistic than the single-channel "mono" sound reproduction our grandparents grew up with. But no one is ever fooled into thinking stereo is the real thing. That's because our ears tell us that the half of a real space that is normally outside our visual field is missing from stereo.

This is particularly true with musical sounds. If you attend live concerts often, you're accustomed to hearing your favorite performing group in an auditorium or stadium, which may have a long and very pronounced reverberation that comes back at you from all directions. A good recording of that group will have an appropriate amount of its natural room sound mixed into it, but stereo can't put it where it belongs. It all comes from up front, between the loudspeakers. Yes, you do hear the sound of your listening room too, but that's the wrong room sound; it isn't the sound of the performing hall. So the reproduction comes across as being not quite right. The only way to reproduce room sound the way we expect to hear it is with a surround system.

Surround Sound is a Long-Running Hit
Surround reproduction is certainly nothing new. Bell Telephone Labs was playing with it 60 years ago, using an array of microphones feeding an array of loudspeakers in another room, and they reported the startling realism it could deliver. And it's been a feature attraction in your nearest theater for the last 20 years. But only recently have we been able to enjoy it at home. We can thank Hollywood for that.

During the 1930s and '40s, people who had been going to the movies every week were spending more and more time at home, listening to radio and records, and Hollywood wanted to lure people back to the theaters by giving them something they couldn't get at home. They were half-heartedly considering multi-channel sound when Walt Disney Studios preempted them all in 1941 with a revolutionary full-length animated film, Fantasia, that featured symphonic music reproduced through four sound channels. It wasn't true surround sound, though, because most of the directional effects were done by switching one or another of three sound tracks to one or another array of loudspeakers. All the front loudspeakers were paralleled, so there was no real stereo at all.

The first true multi-channel sound system accompanied something called "Cinerama" (1952), which used three side-by-side projected images to produce a huge, wrap-around picture. Six soundtracks on a magnetically coated film were synchronized with the optical projectors to provide three stereo channels up front and three separate surround channels at the sides and rear of the theater. It wowed audiences, but it never caught on because the cost of converting an average theater for Cinerama was outrageous, and most of them weren't big enough to accommodate it anyway.

During the 1950s and '60s, Hollywood introduced several widescreen formats—70mm, Cinemascope, Ultra-Panavision, Todd-AO, and so on—and many large theaters could accommodate these. All the widescreen systems used at least four discrete sound channels (three in front and one for the surrounds), and several used six. All depended on synchronized magnetic tape for the sound. The home audio consumer hadn't been left out completely; he got two-channel stereo.

A Wiggle Plus a Waggle Gave Us Stereo
The LP had been around since 1948, and like the 78-rpm discs before it, it used what was called lateral modulation: The sound vibrations wiggled the groove from side to side. Radio broadcasts, on the other hand, used vertical modulation, because the grooves could be spaced closer together to cram more playing time on each disc side. Then it occurred to some bright soul that, since lateral modulation didn't move the groove vertically at all, and vertical modulation didn't move it from side to side at all, why not use each modulation "axis" to record one channel of a stereo signal?

In its final incarnation, the stereo LP used neither vertical nor lateral modulation. It was found that the channels could be made to match one another better if their modulation axes were symmetrical, so both were simply rotated by 45 degrees so that one wiggled diagonally up and down to the left of the groove path and the other to the right. The stereo LP was debuted in 1958.

During the '70s, a young engineer named Ray Dolby perfected a system for encoding a surround channel into two optical tracks on 35mm film, making it cheaper than ever for small theaters to buy into surround sound. It also made it possible to record a surround channel on stereo LPs, and the record industry unleashed "Quadraphonic Sound" amidst much fanfare and foofaraw. Music lovers didn't care and audiophiles didn't like the fact that all the decoders sounded lousy. It was a spectacular failure.

It took home video to make surround sound respectable. When movie video cassettes went stereo, the encoded 35mm soundtracks were transferred directly to tape with their surround signal intact, but it was still some years before the publice knew what was buried there. When consumer surround decoders made it possible to recover the encoded signal, the home theater revolution was on its way.

Dolby's Got You Surrounded
Today, almost every movie on cassette and laserdisc has Dolby Surround on it, and people who aren't yet equipped to reproduce it are missing half the fun. With surround sound, you don't sit outside the world of movie sound; you're immersed in it. A voice, the ominous snap of a twig, the opening of a door, can come from behind you just as it does in the theater. Airplanes and spaceships thunder through the room and over your shoulder, and you can find yourself right in the middle of a noisy crowd or a wet, cold downpour.

The speakers needed to create surround, or "ambient," effects aren't space-hungry. They can be much smaller than the front speakers, and may be mounted high on the walls or from the ceiling. Some can even be located right next to your favorite seat without calling attention to themselves. As long as they aren't in front of you, the surrounds will do what they're supposed to do: wrap you in sound.

The thing that makes all this possible is something called matrixing. When a Dolby Stereo film track is mixed at the stu dio, the surround information is subtracted from the front-channel left and right signals, leaving a "hole" in the L and R signals. In playback, both stereo signals are split into two identical L/R pairs. One pair is fed directly to the front stereo speakers. The signals from the other pair are subtracted from each other, and what's left over is the information that was originally used to dig the hole—the surround signal. (This is an over simplification. For a more detailed explanation, see the adjoining sidebar, "The Mathematics of Dolby's Mono Surround Sound.")

Kal Rubinson's picture

All that is so much more complex than modern discrete multichannel and, at the same time, so much less efficient or successful in creating convincing surround. It takes the increased data bandwidth that we enjoy today to make real multichannel possible.

eriks's picture

Hey Kal,

I have a background in this subject as I worked for one of Dolby's competitors when Dolby Surround was still being used.

Honestly, the recorded information on Dolby Surround film was _really_ good. The issues with it was not the lack of discrete channels, or bandwidth but rather the steering matrix was far too interested in effects, and how noisy Dolby processors at the time were. I got to listen to prototype discrete decoders that you could adjust this on and let me tell you, the immersion factor could be glorious by just dialing all that down and letting the tracks talk without being constantly micromanaged by the steering matrix.

I'm not saying it's as good as multi-track magnetic, or modern discrete digital tracks. I'm just saying that there was a lot more sound and music in those tracks than most people realize. That it sounded so campy was a choice made by Dolby which recording engineers could not get around.



Kal Rubinson's picture

I will not dispute that but the result, as seen in the open market, was that Dolby Surround had negligible and transient effect on music recordings.

Prior to the appearance of discrete multichannel, I played around with a Meridian system and the experience established my interest in "surround sound" but it was not sufficient to get me to commit to it. Later discrete, albeit lossy, media were a move in the right direction. However, it was not until the arrival of discrete, lossless formats that significant numbers of music recordings became available to justify (for me and others) rebuilding my system from stereo to multichannel.

eriks's picture

If you mean, should you use Dolby Surround for music, I have to agree with you. It was always a system centered on effects, not transparency. I only meant to bemoan how little of the sound on the tracks we would hear because of it.

Have you heard the Neo6 modes for 2 channel music though?

If you ever notice that instruments are brighter at the sides, but less so when in the center, Neo6 fixes this, with none of the downsides of Dolby Surround.

Kal Rubinson's picture

Thanks but I have no real interest in movie sound or HT. In what is probably the reverse of the experience of many, my HT setup is the by-product of my multichannel music interests.

eriks's picture

I understand, but do try Neo6 Music mode for some 2 channel listening. :) It may help you use your center channel more often.

Bogolu Haranath's picture

Have you tried or know about DTS headphone X? ...... Is it supposed to make binaural sound to multi channel surround sound? .........

Kal Rubinson's picture

eriks said:
I understand, but do try Neo6 Music mode for some 2 channel listening. :) It may help you use your center channel more often.

I have but it didn't stick (i.e., not good enough for continued use. OTOH, I do use Auro 2D/3D occasionally.

Bogolu Haranath's picture

My question was directed to eriks ........ Apparently there was a mix up ....... If eriks is reading this, may be he could tell us some thing about DTS headphone X :-) ............

eriks's picture

As you may know, in between Dolby Surround and Dolby Digital there where discrete magnetic tracks for film, both 35mm and 70mm. Not many movies were released in this format, as it required new equipment to read it and the oxide would wear off, and it produced a lot of dust.

The major benefits were noise, extension but also they did away with the DS matrix, so this format was used for musically oriented films like Yentl, The Sound of Music, Amadeus, but also the occasional weird one like The Natural and Caligula. Maybe we should get a BD of Caligula and see what extraordinary musical content they had? :D

tonykaz's picture

...came closest ( am I wrong ? ) to describing a Sonic Holidome experience of replicating "being there", using available gear, making home audio hobbyist's participation a possibility, for the first time that I'm aware of.

Otherwise, isn't 5.1 and it's variations a "sound effects" gimmick?

Mr.KR is the first Serious Audiophile to attempt elevating the genre ( as far as I'm aware of) , there must be something there to enjoy, something otherwise missing.

Sitting in Central Park NY and hearing sounds from all around me, I don't know if I'd like to bring that Sonic Landscape into my home but having the option is thought provoking.

It might even be ADDICTIVE. Phew!!

I'm stay'n tuned.

Thanks for all the reporting on this.

Tony in Michigan

Kal Rubinson's picture

Tony said: Sitting in Central Park NY and hearing sounds from all around me.......

Really? I'm only 4 blocks away!

tonykaz's picture

I was using Central Park figuratively, as a visualization tool, because it has Central as part of the meaning I'm struggling to convey.

I've stayed at the Mark Hotel on the edge of the Park.

I rather love Central Park, NY. if I'm in NY.

Tony in Ice Storming Michigan

Kal Rubinson's picture

Tony said: I've stayed at the Mark Hotel on the edge of the Park.

High tea at the Mark. A delight.

Robin Landseadel's picture

Best "surround" experience—standing the middle of the Berkeley Symphony Orchestra during a rehearsal of Olivier Messiaen's "Éclairs sur l'Au-Dela" during a passage where the woodwinds were performing birdsong—an orchestral aviary.

ednazarko's picture

I was a professional brass player - mostly trombones and tubas - for years, and I really miss how music sounds from inside. Orchestras, where because I sat in the back, my soundstage was reversed from the audience's soundstage. And big bands, where I loved sitting inside back row. The "mix" I remember is also quite different from what comes on recorded music. With classical music I always want the winds mixed louder.

The simulated surround sound function on my pre-pro can get me close to happy from my normal listening spot. I think my taste for dipole plus cardioid speakers (Gradient Revolutions), or open baffle speakers is because the sound envelops more. I find myself dragging a chair in quite close for stereo, or smack in the middle for surround.

I've had some absolutely spooky surround sound experiences with binaural recordings and open back headphones. First time I listened to one album I startled a few times (without thinking whipped around to look) because I heard someone sniffing who seemed precisely placed behind me. I have a handful of binaural recordings, that through the right headphones, beat my 5.1 system for that spooky feeling of being present.

Bogolu Haranath's picture

Some of us also listen to headphones, both closed back and open back ......... May be you could mention few of those binaural recordings? ....... Some of us may be interested :-) ........

ednazarko's picture

Chesky Records (he owns HD Tracks) does a LOT of binaural. Search and find. I recommend Wyclyffe Gordon "Dreams of New Orleans", Amber Rubarth's "Sessions from the 17th Ward", Macy Gray's "Stripped"... and Dunun Kann, drummers from Guinea.

The first binaural recording I ever heard was a poetry reading (via B&W record release.) I had my CIEMs in, on a plane waiting to take off, and that's when I had my near-neck-breaking moment of "someone's got a cold right behind me." Seats in the next two rows were empty... and I had CIEMs on so I'd have never heard that... then it happened again, and "behind me" was the fuselage and window. The effect is there with any headphone, but for me is strongest on open backed.

Chesky records in interesting places - like a couple of churches with great acoustics, so the sense of space is massive, unlike how headphones can present quite a small image. The knock on binaural is that they don't sound great through speakers, but I don't find that to be true. The space and aliveness on Macy Gray's album is just as spooky through speakers.

dc_bruce's picture

stuck on the wall behind you.

It's easy to dismiss these, but Bose was/is on to the central problem of multichannel sound, whether accompanied by video or not. That is, what do you do with all that "stuff" in the room?

Perhaps one reason for the decline of "specialist audio" is its increasing demands on the listening room.

Consider, in the "hi-fi" era, mono reproduction required only one speaker that, perhaps, could be shoved off into an unused corner. And in the early stereo era, before we got all excited about "imaging," "soundstage" and the like, many speakers were just shoved into a bookshelf, or stood on the floor (in a corner!).

Today, it's just about impossible to have a "serious" stereo that doesn't dominate the room, like a sacrificial altar to the audio gods. Even small speakers that used to be called "bookshelf" have been re-labelled "stand mount" speakers that demand to be set on expensive stands, well out into the room.

I think a lot of us, who don't want the stereo to be relegated to the basement and who don't want to cut ourselves off from our family, have come to accept some sonic compromises. And, while the sonic benefits of multichannel are indisputable, for lots of folks those benefits don't outweigh the costs -- financial and otherwise.

ednazarko's picture

My 5.1 system is nowhere near set up the way I'd like, but I was told that I could only have the rear speakers where I wanted them if I wanted a different wife. Sigh. Still, it's good enough for movies, and for the occasional 5.1 mixed album. When she's got a business trip I pull the speakers out to where I want them and binge-listen.

cozmoz's picture

Wonderful details, but the only thing I could not understand the relation between bone conduction and surround sound. How we are going to merge both? One is physical and other one is more extrinsic in nature.

cozmoz's picture

Wonderful details, but the only thing I could not understand the relation between bone conduction and surround sound. How we are going to merge both? One is physical and other one is more extrinsic in nature.