How Do “Surround” Sound Bars Work?

The idea behind a conventional surround sound setup is simple: the speakers surround you, and thus, so does the sound. But a new generation of sound bars, the all-in-one devices that sit below your TV and house multiple drivers in a horizontal layout, also claim to have surround sound capabilities. How can that be possible if the only speaker is directly in front of you?

The simplest answer: most of them don’t. The “surround” feature of a lot of sound bars, especially cheaper models, is just a more exaggerated stereo effect from two or more speaker drivers. But some of the more expensive models, especially the newest ones with Dolby Atmos capability, can simulate a surround sound setup with surprising effectiveness. This isn’t “real” surround sound either—ye cannae change the laws of physics—but it creates a convincing illusion by bouncing sound waves off the walls of the room.

Cheaper Sound Bars Are Better Than TV Speakers, But Can’t Do True Surround

A typical speaker bar or speaker base, up to about $200, is simply a better set of stereo speakers than the one that’s in your television. Though these inexpensive sets can’t even “fake” surround sound, they’re nothing to sneeze at: most will have at least 100 watts or so of power and much clearer, richer sound than the small, back- or down-firing speakers embedded in today’s thin LCD televisions. Some of these sets also include a subwoofer for 2.1 stereo, but even so, the individual drivers are still restricted to, at most, two clusters of sound for standard stereo playback.

A low-end 2.1 speaker bar. Good for improving your TV’s underpowered speakers, not much else.

Now, some of these bars can include a “surround” mode or profile in the software. And that profile might create some extra “space” between the left and right channels of sound, thanks to subtle manipulations of frequency and timing—simulated surround sound headsets do something similar. But you’re still fundamentally listening to only two sound channels, both of them more or less in front of you. For example, this LG 2.1 sound bar ($150) has a subwoofer and six woofer/tweeter drivers, but still only supports two channels of sound.

But what about mid-range sound bars with five different speaker drivers, or even seven? In those cases, each driver is able to play an individual channel from a 5.1 or 7.1 soundtrack, and your ears should be able to pick out all of the sound from each. For example, this Samsung model ($399) has five distinct speakers in the bar, corresponding to the center channel, front left, front right, surround left, and surround right. So you will hear the front, side, and rear channels as individual and distinct sources of sound…but it’s still all coming from in front of you. It’s better than nothing, but still quite a bit removed from a true surround sound setup with speakers correctly placed all around the listener. And frankly, it’s hard to even call it “surround”…it’s just multi-channel audio.

Faux Surround Bars Use the Room to Simulate Multi-Directional Sound

However, if you’re willing to go a bit higher in price, things get interesting. With the advent of advanced surround sound software tools like Dolby Atmos and some clever engineering, the most complex sound bars can create a convincing surround sound simulation in a single contained device (usually with an added subwoofer for the deepest of bass tones). This is achieved by angling the drivers in specific directions to “bounce” the sound waves off of the walls of the room and back towards the listener from different directions.

An all-in-one 7.1 sound bar that uses Dolby Atmos to simulate surround sound.

Check out the video below for a visual example of this surround sound effect, achieving a simulated 5.1-channel setup. This LG sound bar does so with drivers pointing directly out at the listener (center channel), drivers on either side pointing to the left and right and angled slightly forward (left surround and right surround), and drivers on either side pointing up and slightly forward (rear left and rear right) to bounce the sound off the ceiling.

This is some extremely cool technology, and not just because of the novelty of sticking all that audio power into a single bar. Trying to achieve the same sound-bouncing effect with a regular set of 5.1-channel speakers wouldn’t work. It’s Dolby’s Atmos audio processing, which makes subtle adjustments to volume, timing, and frequency on the fly, that allows the sound to fool your brain into thinking it’s coming from multiple directions at once.

Of course, depending on the layout and geometry of your living room to provide sources of reflected sound is less than ideal. The best effect will be experienced by those with a television and seating arrangement perfectly centered in the room, with walls symmetrical walls on either side, ceilings that aren’t especially high or vaulted, and generally have a rear wall about the same distance from the listener as the TV. That’s a lot of variables to work with—for example, if you have an open kitchen to the left of your living room, the surround channels bounced to the left will be softer and less distinct than the right.

However, this impressive technology is predictably expensive. The LG SJ9 model in the video goes for about $900, and a similar model from Sony is almost $1300. Yamaha offers a similar design for only $300, but it uses the less widely-available DTS x Virtual 3D standard, and may not work with all media types.

The Only True Surround Sound Comes with Separate Speakers

A 5.1 speaker set with a front speaker bar. True surround sound, but not all-in-one.

There is one other type of surround sound bar in between those two price ranges: a four-piece, true surround setup. Some sound bars come with a subwoofer and two smaller rear channel speakers that can deliver actual surround sound, typically in a 5.1 arrangement (with the center, left, and right channels all coming from the main bar in front). This $230 Sony model is a good example. This is true surround sound, but it’s not anything particularly noteworthy: it’s basically just consolidating three speakers into a single piece for a better aesthetic effect. It doesn’t really fit into the same category as the above options, and isn’t what most people are looking for when they think “sound bar”.

Should You Get a Surround Sound Bar?

So are these worth getting? It depends. The plain fact of the matter is that multi-speaker surround setups are now much cheaper than the super-premium sound bars that can create a surround sound effect. For example, an LG-branded true 5.1 set with distinct channel speakers and the same 500 watt power rating as the sound bar above is only $250, less than a third of the sound bar’s retail price (and including a Blu-ray player!).

Surround setups are complicated, though, and aren’t always as aesthetically pleasing. So if there’s no practical way for you to run wiring for surround sound speakers all the way around a room, or if your home’s decor is so important that you just can’t stand to see those extra speakers, then a surround sound bar might be the best option. Assuming you can afford it, of course—this is a literal case of form (and price tag) over function.

Image source: LG, Amazon, Sony

Michael Crider has been covering technology on the web since 2011. His interests include folk music, football, science fiction, and salsa verde, in no particular order. He wrote a novel called Good Intentions: A Supervillain Story, and it's available on Amazon. You can follow him on Twitter if you want.