What Surround Sound Is and How to Get It

Expand your movie and music listening experience

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.

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

Since the mid-1990s surround sound has been an integral part of the home theater experience, and, with that, there is an abundance of surround sound formats to choose from.

The Big 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. Just about every home theater receiver producer has additional third-party partnerships with one or more companies that offer their own twists to enhance your surround experience.

What You Need to Access Surround Sound

To experience surround 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 soundbar.

However, the number and type of speakers, or soundbar you have in your setup is just one part of the equation. To get the benefit of surround sound, you also need to access audio content that your home theater receiver, or another compatible device, has the ability to decode or process.

Surround Sound Decoding

One way to access surround sound is via an encoding/decoding process. This requires the surround sound signal to be mixed, encoded, and placed on a Disc, stream-able audio file, or another type of transmission 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 sends the encoded signal via a digital optical/coaxial or HDMI connection to a home theater receiver, AV preamp processor, or another compatible device that can decode the signal, and distribute it to the appropriate channels and speakers so that it can be heard by a listener.

Examples of surround sound formats that fall into the above 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 to access surround sound is via surround sound processing. This is different than encoding/decoding. Although you need a home theater, AV processor, or a sound bar to access it, it doesn't require any special encoding process on the front end.

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 embedded cues that provide an indication where those sounds might be placed if it were in an encoded surround sound format.

Although the results are not as accurate as surround sound that uses an encoding/decoding system, it provides an acceptable surround sound experience for most content.

Most surround sound processing formats can take any two-channel stereo signal and "upmix" it to 4, 5, 7, or more channels.

If you 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 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), and 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 an extra-wide channel or front height channel or both).
  • Auromatic by Auro3D Audio – Works in a similar fashion as the Dolby Surround and DTS Neural:X upmixers.

THX offers up sound enhancement modes designed to optimize the home theater listening experience for movies, games, and music.

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 Soundbars. This is where virtual surround sound comes in.

Virtual surround sound enables a soundbar 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 soundbar 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), Dolby Virtual Speaker (Dolby), and DTS Virtual:X.

Virtual surround is not true surround sound, 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 operates in one of two ways. it can take a two-channel signal and give a surround sound-like treatment or 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.

Virtual Surround sound can also be used to provide a surround sound listening experience in a headphone listening environment.

Ambiance Enhancement

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

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

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

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...).

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