AudioAudio: Guides

Everything About Surround Sound Audio and Its Formats

surround sound audio and its formats

The appeal of going to see a movie at the theatre rather than at home is not just the big screen, but also the way the sound works. Movie sound systems are designed to immerse you in the scenes themselves, thus improving your overall experience.

Surround sound systems have come such a long way now that they are no longer limited to movie theaters. You can set up such systems in your home easily, whether it’s for gaming or Netflix! But before you do this, you need to have a fundamental understanding of the different surround sound formats, and the results they give you.

A Brief History

In 1969, surround sound was made available to the home for the first time. The first version was called Quadraphonic sound and simply consisted of four speakers placed at each corner of the room. This phenomenon was short-lived, and trouble arose when companies began to battle over formats.

Again in 1982, Dolby Surround was introduced by Dolby Laboratories, and the surround sound home system made a comeback. Dolby and DTS are among the brands responsible for the popularity of surround sound systems today, and for new and innovative formats.

The Basic Components of Surround Sound

Even though we have everything from early surround sound systems to wireless surround sound available now, most systems use the same basic components and technology. Having a basic understanding of these will help you understand how different formats work.

First and foremost are the speakers. At its simplest configuration, surround sound has two main speakers at the front which are stereo based, and then two surround speakers placed at optimal points in the room. Modern systems also include a fifth speaker which is meant specifically for dialogue.

Encoding mechanisms are also very important. Early “matrix” based formats include Dolby Surround and were designed keeping in mind the audio of VHS tapes and such. The matrix further evolved into Pro Logic based formats such as Dolby Pro Logic.

Earlier versions of either mechanism had limitations; each speaker played the same sound with very little variation (the kind used to create an immersive home theatre environment today) because limited space meant limited bandwidth.

Surround Sound Formats

Using Dolby, DTS, and the lesser-known ones like THX, we’re now going to breeze through the most important surround sound formats that you need to know about.

Dolby Digital 5.1

Dolby Digital was the first format that improved on its predeceasing Pro Logic by increasing bandwidth. This has 5.1 surround sound, which means that it can support five discrete and full-bandwidth channels, as well as one discrete subwoofer channel (hence the .1). Many 5.1 devices support wireless surround sound.

This was one of the first surround sound systems to hit home theaters and is still regarded as a standard by many. Dolby Digital 5.1 surround sound is for most DVDs (including Blu-ray), certain video games, some cable and satellite TV, and some broadcast HDTV.

Dolby Digital EX and Digital Plus

Dolby Digital Ex expands Dolby Digital 5.1 into a 6.1 channel by adding a matrixed, full-bandwidth channel. It can still work with audio designed for Digital 5.1, and it adds more depth. Dolby Digital Plus further expands Digital Ex into a 7.1 surround sound channel by using seven discrete, full-bandwidth channels and a subwoofer. Both formats work with DVD, Blu-ray, and when streaming content.

DTS 5.1

DTS 5.1 has the same specs as Dolby Digital 5.1 and was introduced as a rival. Dolby had dominated the audio market for years, but in 1993, DTS came along with sound mixing services for movies (like Jurassic Park) and eventually created its own home theater system.

DTS 5.1 is slightly higher quality sound because it has a higher bit rate, but this difference can be negligible to the average user’s ears. Initially, DTS 5.1 was only supported by a limited selection of DVDs and CDs, but this is no longer the case.

Dolby Pro Logic

As you know by now, this was one of the first surround sound formats to be widely available. It had only two discrete full-bandwidth channels to begin with, as well as one matrixed full-bandwidth channel and one matrixed limited bandwidth channel.

Pro Logic is stereo based and supported by most Digital Dolby sources, but it isn’t used much anymore. It was initially meant for VHS movies and broadcast TV programs that were surround-encoded.

Dolby Pro Logic II

This brought 5.1 stereo sound support to the OG Pro Logic model, and also improves on it by replacing the two matrixed channels with three full-bandwidth matrix channels, and adding a subwoofer channel for bass management.

This format works well with non-HD TV channels, certain video games, and stereo-based audio in general.

Dolby Pro Logic IIx

Pro Logic IIx levels things up by having not three, but five full-bandwidth matrix channels, with the other channels remaining the same. This is 7.1 surround sound format, but some models also use 6.1. Pro Logic IIx further deviates into gaming, movie, and music modes; making it more versatile.

Dolby Pro Logic IIz

Pro Logic IIz also works with 7.1 surround sound, but it is designed to go up to 9.1. It does so by adding two new speakers to the front, along with the traditional surround sound speakers. By introducing sound from a new location in the room, it manages to add more depth to an existing soundtrack.

The five matrix channels in IIx thus become 7 full-bandwidth, matrixed channels, working with 7 discrete, full-bandwidth channels and the bass subwoofer.

DTS Neo:6

As the name suggests, DTS Neo:6 was one of the first formats to use 6.1 sound exclusively. It does work with lower ranges like 5.1 too though.

DTS Neo:6 has two discrete, full-bandwidth channels, and three or four (but usually four) matrixed, full-bandwidth channels. The subwoofer is for bass management. DTS Neo:6 functions in ways similar to Pro Logic II and IIx, and can work with audio material such as vinyl records, stereo soundtracks, and broadcast TV.


When Pro Logic moved on to IIz, DTS Neo moved on to X. This is an 11.1 bandwidth channel, so it really changes the whole game. A DTS Neo:X processor is designed to be able to work with other kinds of sound channels too, so even with lower versions like 5.1, it manages to improve the sound environment.

Some people like to scale down DTS Neo:X to work with 9.1 or 7.1 surround sound channels, in setups where the extra channels from the 11.1 designed are “folded” with the existing lower channel being used. This reduces effectiveness though, and why would you want to downgrade from an 11.1 channel anyway?

Dolby TrueHD

Dolby TrueHD is a 7.1 channel and uses seven discrete, full-bandwidth channels along with one discrete subwoofer. Since it’s meant for more HD soundtracks, it uses a lossless format for more accurate and detailed surround sound.

This format was introduced for HD DVDs and Blu-ray, but it can be used with a number of other sources using an HDMI cable.

DTS-HD Master Audio

DTS-HD Master Audio is, again, the rival for Dolby TrueHD. It uses a similar lossless format for detailed surround sound, and a 7.1 channel with a similar structure. It uses wider frequency ranges and higher sampling rates than other DTS formats.

This was also designed for Blu-ray and similar HD DVDs, but can be used with an HDMI cable just like its competitor. The only difference is that DTS-HD Master Audio can also be used as a 5.1 channel by downgrading.

Dolby Atmos

Dolby Atmos was introduced in 2012 as a sound system for commercial movie theatres, but soon it was adjusted for home use. And it really does bring out the big guns. While in home theatres, Dolby Atmos works with all channels 5.1.2 and up, it has been known to support up to 64 channels and offers a wide range of possible setups.

Another thing about this format is that it also adds two more speakers to the ceiling, either by being in-ceiling ones or Dolby speakers angled to reflect sound off the ceiling. Dolby Atmos is one of the first more modern systems that aims to create a more 3D surround sound experience (but we will discuss a few more formats like this). Dolby also partners with home theatre system makers to create unique surround sound systems with this format.


DTS:X is not as versatile as Dolby Atmos, but it does give similar results. It also opts for a more 3D surround sound and a deeper sound stage, but it requires encoded content (in contrast, Dolby Atmos requires specific speaker layouts and DTS:X does not).

You can always use a decoder though, and this format thus works with any channels 5.1 and above.

THX Surround EX

THX Surround EX is a lesser-known surround sound format but a pretty good niche one. It is a 6.1 channel that used five discrete, full-bandwidth channels, one matrixed, full-bandwidth channel, and one discrete subwoofer.

THX Surround Ex is a good option because it can decode pretty much any Dolby Digital or Dolby Digital EX source, and can also enhance certain Pro Logic, Pro Logic II, and DTS sources.

Auro 3D Audio

Auro 3D has been around longer than Dolby Atmos and DTS:X, but it hasn’t been as popular because its systems are the most complex to set up. It starts from 5.1 surround sound channels and goes up to 11.1, and like its competitors, it offers an immersive sound experience.

Auro 3D has a Level 1 setting that can be upgraded to Level 2. Ceiling speakers are a part of each setting in varying degrees. One ceiling speaker, called VOG (Voice of God) mounts directly above the listening position and is mandatory in both levels.

Auro 3D uses a minimum of ten speakers, adding to the complexity of it all, but it also includes a decoder and sound mixer that can provide a similar experience with formats from other companies.

Audyssey DSX

Audyssey DSX is another lesser-known surround sound system. DSX stands for Dynamic Surround Expansion, and it goes up to 7.1 channels. This doesn’t require encoding, and it allows two additional vertical speakers at the front for an optimum surround sound experience.

Tips for Setting up Your Own System

While choosing an appropriate format will depend on your needs and will require some taking some time before making a decision, here are some quick tips that can come in handy when you decide to set up your surround sound system.

  • If you want to start small, try soundbars first. These can be individual ones or ones that have separate wireless surround speakers.
  • To level up from there, you can even try to DIY a surround sound system by adding an AV receiver and more speakers to your existing soundbar.
  • If you’re starting from scratch then, no matter what your budget, try to spend most of it on speakers, choosing quality over design.
  • Since technology has come a long way, wireless surround sound systems are pretty common now, as are ones that work with Google Home or Alexa, so maybe look into these as well.

Conclusion: Is Surround Sound Worth Looking Into?

The short, and perhaps only, the answer is yes. Take a look at your TV. It is likely quite slim because newer models are getting thinner and thinner; leaving less room for speakers. This means that any external sound source you use will probably sound better than your TVs squeaky audio, but if you’re going down that route then you might as well be smart about it.

Surround sound is a much more natural way to experience sound since it tries to mimic the real world. The most important thing to remember is to do your research and invest in a system because it suits you, not because it’s fancy and flashy.

About author

A finance major with a passion for all things tech, Uneeb loves to write about everything from hardware to games (his favorite genre being FPS). When not writing, he can be seen in his natural habitat reading, studying investments, or watching Formula 1.
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