What Is Surround Sound and How Do I Get It?

Home Theater Surround Sound Setup
Home Theater Surround Sound Setup. Getty Images - adventtr

What Surround Sound Is

 Surround sound is a term applied to several types of formats that enable the listener to experience sound coming from multiple directions, depending on the source material.

Since the mid-1990's surround sound has been an integral part of the home theater experience, and, with that, has comes a history of surround sound formats to choose from.

The Players in the Surround Sound Landscape

The main players in the surround sound landscape are Dolby and DTS, but there have been/and are others, such as Auro Audio Technologies.

Also just about every home theater receiver maker has, in addition including technologies by one or more of those companies, also offer their own added twists to enhance the surround experience.

What You Need To Access Surround Sound

To experience sound sound, you need a compatible home theater receiver supporting a minimum 5.1 channel speaker system, an AV preamp/processor paired with multi-channel amplifier and speakers, home theater-in-a-box system, or a sound bar.

However, the number and type of speakers, or the sound bar, you have in your setup is only one part of the equation. In order to get the benefit of surround sound, you also need to access audio content that your home theater receiver, or other compatible device, has the ability to decode or process. This can be done in several ways.

Surround Sound Decoding

One way to access surround sound is via an encoding/decoding process. This method requires that the surround sound signal be mixed, encoded, and placed on Disc or stream-able audio file, by the content provider (such as a movie studio).

An encoded surround sound signal must be read by a compatible playback device (Ultra HD Blu-ray, Blu-ray, DVD), or a media streamer (Roku Box, Amazon Fire, Chromecast).

The player or streamer then sends this encoded signal via a digital optical/coaxial or HDMI connection to a home theater receiver, AV preamp processor, or other compatible device that can decode the signal, and distribute to the appropriate channels and speakers so that it can be heard by a listener.

Examples of surround sound formats that fall into this category include: Dolby Digital, EX, Dolby Digital Plus, Dolby TrueHD, Dolby Atmos, DTS Digital Surround, DTS 92/24, DTS-ES, DTS-HD Master Audio, DTS:X, and Auro 3D Audio.

Surround Sound Processing

Another way that you can access surround sound is via surround sound processing. This is different, in that although you need a home theater, AV processor, or a sound bar to access it, it does not require any special encoding process on the front end.

Instead, surround sound processing is accomplished by the home theater receiver (etc...) reading the incoming audio signal (which can be analog or digital) and then looking for already imbedded cues that provide an indication where those sounds might be placed if it were in a encoded surround sound format.

Although the results are not as accurate as surround surround that uses an encoding/decoding system, the content does not have be previously surround sound-encoded.

What is great about these concept is that you can take any two-channel stereo signal and "upmix" it to 4, 5, 7, or more channels, depending on the surround sound processing format used.

If you have ever wondered what your old VHS Hifi tapes, Audio Cassettes, CDs, Vinyl Records, and even FM stereo broadcasts sound like in surround sound, surround sound processing is the way to do it.

Some surround sound processing formats that are included on many home theater receivers, and other compatible devices, include Dolby Pro-Logic (up to 4 channels), Pro-Logic II (up to 5 channels), IIx (can upmix 2 channel audio up to 7 channels or, 5.1 channel encoded signals up to 7.1 channels), and Dolby Surround Upmixer (which can upmix from 2, 5, or 7 channels to a Dolby Amos-like surround experience with two or more vertical channels).

On the DTS side, there is DTS Neo:6 (can upmix two or 5 channels to 6 channels), DTS Neo:X (can upmix 2, 5, or 7 channels to 11.1 channels), anf DTS Neural:X (which functions in a similar fashion as the Dolby Atmos upmixer).

Other surround sound processing modes include Audyssey DSX (can expand a 5.1 channel decoded signal by adding both a an extra wide channel or front height channel or both.

Also, Auro 3D Technologies also makes available its own audio processing format that works in a similar fashion as the Dolby Surround and DTS Neural:X upmixers.

Even THX offers up surround sound processing modes that are designed to optimize the home theater listening experience for movies, games, and music.

As you can see there are a lot of surround sound decoding and processing options available, depending on the brand/model of your home theater receiver, AV processor, or sound bar, but that isn't all.

In addition to the surround sound decoding and processing formats above, some home theater receivers, AV processors, and sound bar makers add their own flavor with formats such as Anthem Logic (Anthem AV) and Cinema DSP (Yamaha).

Virtual Surround

While the above surround decoding and processing formats work great for systems with multiple speakers, something different needs to employed with Sound Bars - this is where virtual surround sound comes in. Virtual surround sound enables a sound bar, or other system (sometimes offered in a home theater receiver as another option) that provides a "surround sound" listening with just two speakers (or two speakers and subwoofer).

Known by several names (depending sound bar brand) Phase Cue (Zvox), Circle Surround (SRS/DTS - Circle Surround can work with both un-encoded and encoded sources), S-Force Front Surround (Sony), AirSurround Xtreme (Yamaha), and Dolby Virtual Speaker (Dolby), virtual surround is actually not true surround sound at all, but a group of technologies that, by employing phase-shifting, sound delay, sound reflection, and other techniques, tricks your ears into thinking you are experiencing surround sound.

Virtual surround can work in one of two ways, it can either a take two-channel signal and give a surround sound-like treatment, or it can take an incoming 5.1 channel signal, mix it down to two channels, and then use those cues to provide a surround sound experience using just the two available speakers it has to work with.

Another interesting thing about Virtual Surround sound is that is can be used to provide a surround sound listening experience in a headphone listening environment. Two examples are Yamaha Silent Cinema, and Dolby Headphone.

Ambience Enhancement

Surround sound can be further complements via the implementation of Ambience Enhancement. On most home theater receivers, added sound enhancement settings are provided that can add ambience to surround sound listening, whether the source content is decoded or processed.

Ambience enhancement has its roots in the use of Reverb to simulate a larger listening area back in the 60's and 70's (used a lot in car audio), but frankly, as applied at the time, could be very annoying.

However, the way that the reverb content is implemented these days, is via sound or listening modes provided on many home theater receivers and AV processors. The modes add more specific ambience cues that are supposed to be tailored for specific types of content or simulate the ambience and acoustic properties of specific room environments.

For example, there may be listening modes provided for Movie, Music, Game, or Sports content - and, in some cases it gets even more specific (Sci-Fi movie, Adventure Movie, Jazz, Rock, etc...).

However, there is more. Some home theater receivers also include settings that simulate the acoustics of room environments, such as a Movie Theater, Auditorium, Arena, or Church.

The final touch that is available on some high-end home theater receivers, is the ability for users to further tailor pre-set listening mode/ambience settings manually to provide a better result by adjusting factors such as room size, delay, liveness, and reverb time.

The Bottom Line

As you see, Surround Sound is more than just a catch-phrase. Depending your available content, playback device, and room characteristics, there are a lot of listening options that can be accessed and tailored to your needs and preferences.