Surround Sound Formats Guide

A rundown of surround sound formats available for home theater systems

Illustration of room with surround sound

 

jorgenjacobsen / Getty Images

Surround sound is integral to the home theater experience. The following list spotlights the most common surround sound formats. They are listed in alphabetical order, accompanied by a brief explanation with a link to more detailed articles.

If you'd like to dig deeper into the history and basics of surround sound, and what you need to set up your own system, refer to our companion articles here:

Audyssey DSX

Audyssey DSX Speaker Placement Example
Audyssey

Audyssey DSX (Dynamic Surround Expansion) is a surround sound processing format that allows for the addition of two vertical-height speakers in the front. It also include the normal left/right wide speakers found in a 5.1 arrangement. There is no content encoded with this format. Instead, a home theater receiver that uses Audyssey DSX analyzes the embedded sound cues in a 2, 5, or 7 channel soundtrack, and then expands the sound field to the corresponding speaker layout.

Auro 3D Audio

Auro3D-logo-and-diagram.jpg

D&M Holdings

Auro 3D Audio is one of the youngest formats available but also one of the most complex. It is a consumer version of the Barco Auro 11.1 channel surround sound system used in cinemas.

In the home theater space, Auro 3D Audio is a competitor to the Dolby Atmos and DTS:X immersive surround sound formats. Auro 3D Audio starts with a 5.1 channel speaker layout, but there is another set or layer of front and surround speakers directly above the main listening position. These are referred to as level 1 and level 2.

To get the full benefit of Audio 3D Audio, you need to include one ceiling mounted speaker placed directly above the listening position. This added option is referred to as the VOG channel (Voice of God). The total number of speakers (not including the subwoofer) is 10.

Auro 3D Audio is both a decoding and processing format. If a Blu-ray Disc or other compatible content source is encoded with Auro 3D audio, and your home theater receiver has the necessary decoder, it will distribute the sound as intended. However, the Auro 3D Audio system also includes an up mixer, so you can get some of the benefits of Audio 3D Audio on standard 2, 5, and 7 channel content.

Access to the Auro 3D Audio format is only available on select high-end home theater receivers and AV preamp processors.

Dolby Atmos

dolbyatmos-soundfielda.jpg

Onkyo USA / Dolby Labs

Dolby Atmos is a surround sound configuration that launched in 2012. It was introduced as a commercial cinema format with up to 64-channels of surround sound, combining front, side, rear, back, and overhead speakers. Dolby Atmos surround sound encoding format is designed to provide a completely immersive listening experience.

Adapted for home theater use, Dolby Atmos is available on select Blu-ray and Ultra HD Blu-ray Disc releases. It provides several speaker setup options, depending on the brand and model of the home theater receiver. The options may require 7, 9, or 11 total channels.

For the best results, it is recommended to employ ceiling mounted speakers for the height channels. However, Dolby, in partnership with several home theater makers, have developed standards for vertically firing speakers. These can be incorporated into both bookshelf and floor standing designs, or as separate modules to be placed on top of the most current bookshelf or floor standing speakers.

Dolby Digital, Dolby Digital EX, Dolby Digital Plus

The Dolby Digital Family

Dolby Labs

Dolby Digital is a digital encoding system for audio signals that can be decoded by a receiver or preamplifier with a Dolby Digital decoder.

Dolby Digital is often referred to as a 5.1 channel surround system. However, it must be noted that term "Dolby Digital" refers to the digital encoding of the audio signal, not how many channels it has. In other words, Dolby Digital can be Monophonic, 2-channel, 4-channel, or 5.1 channels. Most commonly, Dolby Digital 5.1 is referred to as "Dolby Digital."

Dolby Digital EX is based on the technology already developed for Dolby Digital 5.1. This process adds a third surround channel directly behind the listener. In other words, the listener has both a front center channel and a rear center channel. If you are losing count, the channels are labeled: Left Front, Center, Right Front, Surround Left, Surround Right, Subwoofer, with a Surround Back Center (6.1) or Surround Back Left and Surround Back Right. This requires another amplifier and a special decoder in the Surround Receiver.

Dolby Digital Plus expands the Dolby Digital family up to 7.1 channels. This means that, in addition to left and right surround speakers, it provides the ability to accommodate a pair of left and right surround back speakers.

Dolby Digital and EX soundtracks are available on DVD, Blu-ray Discs, and some streaming content, while Dolby Digital Plus is available on Blu-ray and some streaming content.

Dolby Pro Logic, Prologic II, and IIX

Dolby Pro Logic II logo

Dolby Labs

Dolby Pro Logic extracts a dedicated Center Channel and Rear Channel from two-channel content. The Center Channel more accurately centers the dialog in a movie soundtrack. There is also rear channel is passes a monophonic signal, which limits rear-to-front and side-to-front motion and sound placement cues.

Dolby Pro Logic II is a surround sound processing technology, developed jointly by Jim Fosgate and Dolby Labs. This system can create a "simulated" 5.1 channel surround environment from any two-channel source, as well as from a 4-Channel Dolby Surround signal. Although different than Dolby Digital 5.1 or DTS, in which each channel goes through its own encoding/decoding process, Pro Logic II makes effective use of matrix-ing. This delivers an adequate 5.1 representation of a stereo film or music soundtrack.

Dolby Pro Logic IIx is an enhancement to Dolby Pro-Logic II. It includes the addition of two back channels, as well as as Dolby Pro-logic II's 5.1 channels. This makes Dolby Pro-logic IIx a 7.1 channel surround processing system.

Dolby Pro Logic IIz

Dolby ProLogic IIz Height Speakers

Dolby Labs

Dolby Pro Logic IIz is a surround sound processing format that is a predecessor to Dolby Atmos. Unlike Dolby Atmos, content does not have to be specially encoded, which means that any 2, 5, or 7 channel sources can benefit. Dolby Pro Logic IIz offers the option of adding two more front speakers placed above the left and right main speakers. This feature adds a "vertical" or overhead component to the surround sound field—great for rain, helicopter, or plane flyover effects. Dolby Prologic IIz can be added to either a 5.1 channel or 7.1 channel setup.

Yamaha offers a similar technology on some of its home theater receivers called Presence.

Dolby TrueHD

Official Dolby TrueHD Logo

Dolby Labs

Dolby TrueHD is a high definition digital surround sound encoding format that supports up to 8-channels of decoding. It is bit-for-bit identical to a studio master recording. Dolby TrueHD is one of several audio formats designed for and employed by the Blu-ray Disc format. Dolby TrueHD is delivered from Blu-ray Disc or other compatible playback devices via the HDMI connection interface.

Dolby Virtual Speaker

Dolby Virtual Speaker Logo

Dolby Labs

Dolby Virtual Speaker is designed to create a fairly accurate surround sound experience with just two speakers and a subwoofer. It creates a wider soundstage when used with standard stereo sources, but when sources are combined with Dolby Digital encoded media, the speakers create a 5.1 channel sound image. It accomplishes this by taking into account sound reflection and natural listening conditions. This allows the surround sound signal to be reproduced without needing five, six, or seven speakers.

DTS

Official DTS Digital Surround Logo

DTS

DTS (also referred to as DTS Digital Surround) is a 5.1 channel encoding and decoding surround sound format that is similar to Dolby Digital 5.1. The difference is DTS uses less compression in the encoding process. As a result, many feel that DTS is a better, more accurate listening experience.

While Dolby Digital is mainly intended for film and television, DTS is often used in in music production.

To access DTS encoded information on CDs and DVDs, you must have a home theater receiver or preamplifier with a built-in DTS decoder, as well as a CD or Blu-ray player with DTS pass-through.

DTS 96/24

Official DTS 96/24 Logo

DTS

DTS 96/24 is not so much a separate surround sound format but rather a "upscaled" version of DTS 5.1 that can be encoded onto DVDs. Instead of using the standard DTS 48kHz sample rate, DTS 96/24 uses a sample rate of 96kHz. The bit-depth is also extended from 16 to 24 bits.

What all of the above jargon means is that there is more audio information embedded in the audio, which translates to more detail and dynamics when played back on 96/24 compatible devices.

Even if your source device or home theater receiver is not 96/24 compatible, it can still access the 48kHz sample rate and 16-bit depth present in the soundtrack.

DTS Circle Surround and Circle Surround II

Circle Surround Diagram

DTS

While Dolby Digital and DTS approach surround sound from a directional standpoint (specific sounds emanating from specific speakers), Circle Surround emphasizes sound immersion.

A normal 5.1 source is encoded down to two channels. It is then re-decoded back into 5.1 channels and redistributed to the 5 speakers (plus subwoofer). Through this process, Circle Surround is able to create a more immersive sound experience without losing the directional cues of the original 5.1 source material.

Circle Surround provides enhancement of Dolby Digital and similar surround sound source material without degrading the original intent of the surround sound mix. It also adds a rear center channel, providing an anchor for sounds emanating from directly behind the listener.

DTS-ES

Official DTS-ES Logo

DTS

DTS-ES refers to two 6.1 channel surround encoding/decoding systems: DTS-ES Matrix and DTS-ES 6.1 Discrete.

DTS-ES Matrix can create a center rear channel from existing DTS 5.1 encoded material, while DTS-ES 6.1 Discrete requires that the software already have a DTS-ES 6.1 Discrete soundtrack. DTS-ES and DTS-ES 6.1 Discrete formats are backward compatible with 5.1 channel DTS Receivers and DTS encoded DVDs.

These formats are rarely used on DVDs and are almost non-existent on Blu-ray Discs.

DTS-HD Master Audio

Official DTS-HD Master Audio Logo

DTS

Similar to Dolby TrueHD, DTS-HD Master Audio is a high definition digital-based surround sound format that supports up to 8-channels of surround decoding with increased dynamic range, wider frequency response, and higher sampling rate than other standard DTS formats.

DTS-HD Master Audio is one of the several audio formats designed and employed by Blu-ray Disc and the now discontinued HD-DVD format. To access DTS-HD Master Audio, it must be encoded onto a Blu-ray Disc or other compatible media format. It must also be delivered via the HDMI connection on a home theater receiver with a built-in DTS-HD Master Audio surround sound decoder.

DTS Neo:6

DTS Neo:6

Robert Silva

DTS Neo:6 is a surround sound format that functions similarly to Dolby Prologic II and IIx. If you have a home theater receiver that includes DTS Neo:6 audio processing, it will extract a 6.1 channel field (front, center, right, left surround, right surround, center back) from existing analog two-channel material, such as a stereo CD, vinyl record, stereo movie soundtrack, or TV broadcast. While DTS Neo:6 is a six-channel system, the center-back channel can be split between two speakers.

DTS Neo:X

Official DTS Neo:X Logo with 9.1 Channel Speaker Layout Diagram

DTS

DTS Neo:X was originally introduced as a counter to Dolby's ProLogic IIz and Audyssey's DSX surround sound formats. DTS Neo:X is an 11.1 channel surround sound format that includes front, height, and wide channels.

This format does not require soundtracks mixed specifically for the 11.1 channel sound field. A DTS Neo:X processor is designed to look for cues already present in stereo, 5.1 or 7.1 channel soundtracks that may benefit from an expanded sound field.

DTS Neo:X can also be scaled to work within 9.1 or 7.1 channel environments. Some home theater receivers that feature DTS Neo:X incorporate the 7.1 or 9.1 channel options. In these setups, the extra channels are "folded" with the existing 9.1 or 7.1 channel layout. While not as effective as the desired 11.1 channel setup, it does provide an expanded surround sound experience that is better than the typical 5.1, 7.1, or 9.1 channel layout.

DTS:X

MDA Tool Interface with DTS:X Logo

DTS

Developed in parallel to Dolby Atmos, the DTS:X surround format allows for the placement of sound objects within a three-dimensional space, rather than specific channels or speakers.

Although DTS:X requires encoded content (Blu-ray or Ultra HD Blu-ray), it does not require a specific speaker layout like Dolby Atmos. It works fine with a Dolby Atmos speaker setup. Most home theater receivers that include Dolby Atmos also include DTS:X, though sometimes a firmware update is required.

A properly-equipped home theater setup that features DTS:X audio decoding will map a decoded DTS:X signal to 2.1, 5.1, 7.1, or any one of several Dolby Atmos speaker setups.

DTS Virtual:X

DTS Virtual:X Logo and Illustration

Xperi / DTS / PRNewswire

DTS Virtual:X is an innovative surround sound processing format that projects a height/overhead sound field without the need for extra speakers. Using complex algorithms, your ears are fooled into hearing height, overhead, and even rear surround sound.

Although not as effective as having actual height speakers, it does cut down on speaker clutter. DTS Virtual:X can add height enhancement to both two-channel stereo and multi-channel surround sound content. It is best suited for use in soundbars, where all the speakers are housed within a single cabinet. However, it can be applied to home theater receivers as well.