Encompass sound is precisely what it seems like: a class of merchandise and applied sciences designed to immerse you in audio from all sides, all angles, and, more and more, from all heights too.
We’re going to take a really deep dive into precisely the way it works and the applied sciences that introduced us to as we speak’s state-of-the-art. That features {surround} sound applied sciences, 3D audio codecs like Dolby Atmos, and every thing you want to learn about getting nice {surround} sound — together with hyperlinks to our guides on extra particular matters. Let’s begin with a have a look at the newest Dolby Atmos, presently one of the crucial vital requirements to search for when placing collectively a house theater.
Objectively higher sound
Fluance
Movie show audio system have all the time been in a position to crank out some severe decibels, however earlier than Dolby Atmos, they weren’t all that subtle by way of their underlying tech. As an illustration, for those who had been watching an motion film and there was an explosion on the fitting facet of the display screen, half of the audio system within the theater would all play that very same sound.
With Atmos, the sounds in a theater might now come from distinct areas decided by the skilled audio mixers that had organized them. Recognized within the trade as “object-based” sound expertise, Atmos allowed for as much as 128 distinct sound objects to be represented in a given scene, which might be routed to as much as 64 totally different audio system.
Rivals like Digital Theater Techniques (DTS) quickly adopted go well with, with the corporate boasting that its DTS:X expertise might produce extra particular person audio feeds than Atmos, which was hard-capped at 64. This meant that, theoretically, theater operators had been restricted solely by their urge for food so as to add further audio system and amplification.
With the event of appropriate AV receivers, the battlefield shortly shifted to the lounge. Immediately, most high quality AV receivers help object-based {surround} sound, and the tech that helped revitalize film theaters was made obtainable within the house.
Digital music has additionally gotten the Atmos therapy, with quite a few streaming providers (Tidal, Amazon Music, and Apple Music, to call a number of) already profiting from Dolby Atmos Music, an offshoot of its theatrical, object-based sound expertise.
Atmos isn’t the one payer on this house, both, as rivals like DTS:X and Sony’s 360 Actuality Audio will look to problem Dolby for sonic supremacy within the months and years forward.
This being a top-to-bottom {surround} sound information, nonetheless, we have to journey again earlier than we are able to transfer ahead. For those who’re a layperson seeking to perceive how Atmos and its rivals can revolutionize your house theater, you’ll want a fast {surround} sound primer and a short historical past lesson earlier than constructing your setup.
Encompass sound 101
We’ll get to the historical past of {surround} sound and the specs of all of the competing codecs in only a minute — however first, let’s get the fundamentals out of the way in which. Understanding a number of core ideas will assist orient you to be able to comply with the dialog to come back, so right here’s what it is best to know earlier than we get right down to the nitty-gritty:
The audio system
Encompass sound, at its most simple, includes a set of stereo entrance audio system (left and proper) and a set of {surround} audio system, that are often positioned simply to the perimeters and simply behind a central listening place. The following step up includes the addition of a middle channel: A speaker positioned between the entrance left and proper audio system that’s primarily liable for reproducing dialogue in motion pictures. Thus, now we have 5 audio system concerned. We’ll be including extra audio system later (tons extra), however for now, we are able to use this primary five-speaker association as a springboard for entering into the totally different codecs.
The matrix
No, we’re not speaking concerning the sci-fi franchise starring Keanu Reeves. On this case, matrix refers back to the encoding of separate sound indicators inside a stereo supply. This strategy was the idea for early surround-sound codecs like Dolby Encompass and Dolby Professional Logic and was motivated partially by the restricted house for discrete data on early audio-video media, akin to VHS tape.
Professional Logic
Utilizing the matrix course of, Dolby’s Professional Logic {surround} was developed to encode separate indicators inside the principle left and proper channels. Dolby was in a position to permit house audio gadgets to decode two further channels of sound from media like VHS tapes, which fed the middle channel and {surround} audio system with audio. Due to the restricted house, nonetheless, matrixed {surround} indicators got here with some limitations. As an illustration, the {surround} channels in primary Professional Logic weren’t in stereo and had restricted bandwidth. That implies that every speaker performed the identical factor and the sound didn’t contain a lot bass or treble data.
Encompass sound historical past

OK, so now that what {surround} sound is and what the present state-of-the-art tech is able to, let’s speak about how we acquired right here.
It was the summer time of 1969 when {surround} sound first grew to become obtainable within the house. It was referred to as Quadraphonic sound, and it first appeared on reel-to-reel tape. Sadly, Quadraphonic sound, which supplied discrete sound from 4 audio system positioned in every nook of a room, was complicated and short-lived — no because of corporations battling over codecs (sound acquainted?). Immersion in a three-dimensional audio sphere was to not be given up on, nonetheless.
In 1982, Dolby Laboratories launched Dolby Encompass, a expertise that piggybacked a {surround} sound sign onto a stereo supply via matrix encoding. Since then, Dolby, DTS, and others have helped advance the state of house {surround} sound with a wide range of iterations. Within the subsequent part, we hint this evolution — from the usual 5.1 setups to state-of-the-art, object-based {surround}. 
Encompass sound takes form
Dolby Digital 5.1/AC-3: The benchmark
Keep in mind LaserDisc? Although the medium was first invented in 1978, it wasn’t till 1983, when Pioneer Electronics purchased a majority curiosity within the expertise, that it loved any sort of success in North America. One of many benefits of LaserDisc (LD) was that it supplied much more space for storing than VHS tape. Dolby took benefit of this and created AC-3, now often known as Dolby Digital. This format improved on Professional Logic in that it allowed for stereo {surround} audio system that might present larger bandwidth sound. It additionally facilitated the addition of a low-frequency results channel — the “.1” in 5.1 — dealt with by a subwoofer. All the knowledge in Dolby Digital 5.1 is discrete for every channel — no matrixing obligatory. Sorry, Keanu.
With the discharge of the movie Clear and Current Hazard on LaserDisc, the primary Dolby Digital {surround} sound hit house theaters. By the point DVDs got here out in 1997, Dolby Digital had develop into the default {surround} sound format. To at the present time, Dolby Digital 5.1 is taken into account by many to be the {surround} sound commonplace and remains to be included on most Blu-ray discs.
Picture courtesy of Dolby Labs
DTS: The rival
What’s a expertise market and not using a little competitors? Dolby roughly dominated the surround-sound panorama for years. Then, in 1993, DTS got here alongside, offering its personal digital {surround} sound mixing providers for film manufacturing, first hitting theaters with Jurassic Park. The expertise finally trickled right down to LaserDisc and DVD however was initially obtainable on a really restricted choice of discs. DTS makes use of the next bit price and, due to this fact, delivers extra audio data. Consider it as much like the distinction between listening to a 256kbps and 320kbps MP3 file. The standard distinction is noticeable, however as with so many audio-related comparisons, not everybody was offered on it.
6.1: Kicking it up a notch
In an effort to boost {surround} sound by increasing the “soundstage,” house theater corporations created 6.1, which added one other sound channel. The sixth speaker was to be positioned within the heart of the again of a room and was subsequently known as a again {surround} or rear {surround}. That is the place some confusion started to swirl.
Folks had been already used to considering of and referring to {surround} audio system (incorrectly) as “rears” as a result of they had been so typically positioned behind a seating space. Really useful speaker placement, nonetheless, has all the time referred to as for {surround} audio system to be positioned to the perimeters and simply behind the listening place.
The purpose of the sixth speaker is to provide the listener the impression that one thing is approaching from behind or disappearing to the rear. Calling the sixth speaker a “again {surround}” or “{surround} again” speaker, whereas technically an correct description, ended up being simply plain complicated.
To make issues much more complicated, every firm provided totally different variations of 6.1 {surround}. Dolby Digital and THX collaborated to create a model known as “EX” or “{surround} EX.” It makes use of the tried-and-true matrix encoding methodology to embed the sixth channel contained in the left and proper {surround} indicators.
DTS, however, provided two separate 6.1 variations. DTS-ES Discrete and DTS-ES Matrix carry out as their names recommend. With ES Discrete, particular sound data is programmed onto a DVD or Blu-ray disc, whereas DTS-ES Matrix makes use of the identical approach as Dolby Digital EX to extrapolate data from the {surround} channels.
7.1: The spawn of Blu-ray
Picture courtesy of Dolby Labs

Simply when folks began getting used to six.1, alongside got here 7.1 along with HD DVD and Blu-ray discs as the brand new must-have {surround} format, basically supplanting its predecessor. Like 6.1, there are a number of totally different variations of seven.1, all of which add in a second again {surround} speaker.
These {surround} results that when went to only one rear {surround} speaker might now go to 2 audio system in stereo. The data was additionally “discrete,” which implies that each speaker acquired its personal particular data. This growth was enabled, partially, by the large storage potential of Blu-ray.
Those that purchased a devoted again {surround} speaker throughout the shift to six.1 now discovered themselves searching for a brand new, matched pair of again surrounds — sometimes the very same mannequin they’d purchased for the left and proper surrounds.
Dolby provides two totally different 7.1 {surround} variations. Dolby Digital Plus is the “lossy” model. As a substitute of utilizing matrixing, it applies lossy compression to all the discrete audio channels, which helps to take up much less house on a Blu-ray disc. Dolby TrueHD, however, is lossless. Because of this no sound data has been eliminated throughout compression, and it’s as near the studio grasp as you will get.
DTS additionally has two 7.1 variations, which differ in the identical method as Dolby’s variations. DTS-HD is a lossy 7.1 {surround} format, whereas DTS-Grasp HD is lossless.
It’s vital to notice right here that 7.1-channel {surround} mixes usually are not all the time included on Blu-ray discs. Film studios need to choose to combine for 7.1, and so they don’t all the time accomplish that. There are different components concerned, too, with space for storing being chief amongst them. If a bunch of extras are positioned on a disc, there will not be house for added {surround} data. In lots of circumstances, a 5.1 combine could be expanded to 7.1 by a matrix course of in an AV receiver. This manner, these again {surround} audio system get used, even when they don’t get discrete data. That is changing into much less widespread, nonetheless, particularly with regards to 4K Extremely HD Blu-ray discs, which regularly help a number of seven-channel mixes.
9.1: Professional Logic makes a comeback

For those who’ve been searching for a receiver, you will have observed that many provide a number of totally different variations of Professional Logic processing. Within the trendy Professional Logic household, we now have Professional Logic II, Professional Logic IIx, and Professional Logic IIz. Earlier than we proceed, let’s take a fast have a look at what every of them does.
Professional Logic II
Utilizing the identical matrixed four-channel sound as the unique Professional Logic, Professional Logic II can create a 5.1 {surround} sound combine from a stereo supply. Professional Logic II additionally has one other trick up its sleeve: It could separate the {surround} sign into stereo left and proper channels as an alternative of the unique Professional Logic’s dual-mono presentation. This processing mode is usually used when watching non-HD TV channels with a stereo-only audio combine.
Professional Logic IIx
In case your video supply is offered in 5.1 {surround} — and your house theater system helps further audio system — Professional Logic IIx can take that blend and develop it to six.1 or 7.1. Professional Logic IIx is subdivided into film, music, and recreation modes.
Professional Logic IIz
Professional Logic IIz permits the addition of two “entrance peak” audio system which can be positioned above and between the principle stereo audio system. This type of matrix processing goals so as to add extra depth and house to a soundtrack by outputting sounds from an entire new location within the room. Since IIz processing could be engaged with a 7.1 soundtrack, the ensuing format might be referred to as 9.1.
Regardless of the addition of those peak channels, Professional Logic IIz doesn’t allow a real 3D placement of sounds. To allow that, you’ll want Dolby Atmos or DTS:X, which we describe under.
What about 7.2, 9.2, or 11.2?
As we talked about beforehand, the “.1” in 5.1, 7.1, and many others., refers back to the LFE (low-frequency results) channel in a {surround} soundtrack, which is dealt with by a subwoofer. Including “.2” merely implies that a receiver has two subwoofer outputs as an alternative of 1. Each connections output the identical data since, so far as Dolby and DTS are involved, there is just one subwoofer observe. Since AV receiver producers needed to market the extra subwoofer output, the notion of utilizing “.2” was adopted.
For most individuals, a single subwoofer will present ample low-end bass and rumble. Nonetheless, including a second sub can improve this impact, particularly in bigger media rooms. Try our subwoofer placement information to be taught why a second sub could be best for you.
Audyssey DSX and DSX 2
Audyssey, an organization finest recognized for its auto-calibration software program present in lots of as we speak’s AV receivers, has its personal {surround} answer referred to as Audyssey DSX. DSX additionally permits for added audio system past the core 5.1 and seven.1 {surround} codecs, upmixing 5.1 and seven.1 indicators so as to add extra channels. With the addition of entrance width and entrance peak channels on prime of a 7.1 system, Audyssey permits for 11.1 channels of {surround} sound.
There’s additionally Audyssey DSX 2, which provides upmixing of stereo indicators to {surround} sound. With the appearance of object-based 3D codecs like Dolby Atmos and DTS:X in recent times, nonetheless, Audyssey has seen a decline.
3D/object-based {surround} sound
picture courtesy Dolby Labs Dolby Labs
As we talked about earlier, the newest and best growth in {surround} sound is called “object-based” or “3D” {surround}. For viewers, “3D” provides the perfect description of this expertise due to its potential to make sounds really feel as if they’re transferring via house. As an illustration, you may hear a helicopter take off from in entrance of you, hover over your head, after which disappear into the space behind you.
“Object-based,” however, is the moniker most well-liked by the sound professionals who create these 3D soundtracks as a result of it describes their potential to maneuver a single sound-producing object (like a helicopter) wherever in 3D house.
This immersive hemisphere of sound is made potential by including discrete channels for ceiling-mounted or ceiling-facing audio system in AV receivers at house.
As a result of these channels not have to extrapolate their indicators from audio working to different audio system as they did with Professional Logic IIz 7.1, they get their very own quantity. A 5.1.2 system, for instance, would function the standard 5 channels and a subwoofer, however it might additionally function two further audio system including peak data in stereo on the entrance. A 5.1.4 system would add 4 further peak channels to five.1, together with two on the entrance, two on the rear, and so forth.
Dolby Atmos
This shouldn’t come as a shock after studying the remainder of this text, however Dolby is the present chief in object-based {surround} sound expertise. We’ve been over Atmos’ bid to revolutionize the movie show expertise, however what about house theaters?
Atmos within the house

Atmos debuted on appropriate AV receivers in 2015, however in a way more restricted capability than the skilled format. As talked about above, the commonest configurations are 5.1.2 or 5.1.4, which add two and 4 peak audio system to a standard 5.1 {surround} setup respectively, although Dolby helps a lot bigger configurations. Atmos took off comparatively shortly, and most AV receivers above the low-end vary of the spectrum now help the format. In reality, each receiver on the checklist of our favourite AV receivers helps Atmos, even fashions priced at $500 or much less.
In 2015, Yamaha launched the primary Atmos-capable soundbar, the YSP-5600, which makes use of up-firing drivers to bounce hold forth the ceiling.  Since then, soundbar producers have totally embraced Dolby Atmos. Some obtain the Atmos impact utilizing devoted wi-fi {surround} audio system with up-firing drivers to enhance the entrance audio system within the bar. Others use a way often known as virtualized Dolby Atmos to convincingly simulate the Atmos impact utilizing fewer audio system.
Some TVs, like LG’s line of very good OLED TVs, declare Dolby Atmos help via the TV’s built-in audio system. As a result of Dolby Atmos could be calibrated for as few as two channels, we suppose that is technically correct. Nonetheless, patrons must be conscious that two-channel Atmos won’t ever sound pretty much as good as discrete 5.1.2 or higher Atmos.
Motion pictures with Dolby Atmos soundtracks at the moment are quite common on Blu-ray and Extremely HD Blu-ray discs. Furthermore, streaming websites like Netflix, Vudu, Amazon Prime Video, Disney+, and Apple TV+ all provide a choice of Atmos motion pictures and exhibits. Atmos is even beginning to seem in some stay broadcasts. Latest examples embody the 2018 Winter Olympics, the NHRA’s stay drag-racing occasions, and even a number of music festivals.
One factor to remember with Dolby Atmos: It’s a finicky beast. With a purpose to hear Dolby Atmos sound, each a part of your house theater system — from the supply to the audio system — must help it. Right here’s our full information to getting nice Dolby Atmos sound.
Dolby Atmos Music
Tidal
Although nonetheless in its early phases, Dolby Labs has been working with main file labels and streaming providers to develop using Dolby Atmos expertise for music manufacturing. The idea is straightforward: Dolby Atmos Music makes use of all the identical object-oriented 3D audio instruments because the film soundtrack model however places them within the palms {of professional} music producers.
The result’s immersive music that goes nicely past what conventional two-channel stereo and even quadraphonic sound can obtain. Sadly, Dolby Atmos Music could be very restricted in the intervening time. The one solution to hear it utilizing a Dolby Atmos-equipped house theater is to purchase one of many only a few Blu-ray discs that include a Dolby Atmos Music combine, just like the lately remastered and rereleased Kick by INXS.
Amazon Music HD lately grew to become the primary music streaming service to supply Dolby Atmos Music tracks, however the one means you possibly can hear them is by way of Amazon’s Echo Studio 3D sensible speaker.
In a number of choose golf equipment, Dolby Atmos Music is being utilized by DJs and different stay performers to supply an immersive music atmosphere for dance flooring.
Hopefully, Dolby will quickly open the floodgates on Dolby Atmos Music and discover extra methods for people to expertise it.
It’s price noting that Sony additionally has a 3D immersive music format often known as Sony 360 Actuality Audio that competes with Dolby Atmos Music. It too could be discovered on some streaming providers, however as with Atmos Music, the gadgets wanted to listen to it are restricted to just some choices for the second.
DTS:X

Simply because it does with different forms of {surround} sound, DTS has its personal model of object-based audio, DTS:X, which was unveiled in 2015. DTS:X goals to be extra versatile and accessible than Atmos, making use of preexisting speaker layouts in theaters and supporting as much as 32 totally different speaker configurations within the house.
Whereas DTS:X was beforehand tacked on in updates for Atmos-enabled AV receivers, it’s now obtainable with newer AV receivers proper out of the field. Firms like Lionsgate and Paramount provide house releases in DTS:X, however its lack of widespread adoption on disc-based media — and nil adoption amongst streaming providers — is its greatest limiting issue.
DTS Digital:X
DTS additionally acknowledges that not all film lovers have the house or the time to place collectively an object-based sound system. Analysis gathered by DTS confirmed that lower than 30% of shoppers truly join peak audio system to their methods, and fewer than 50% even trouble connecting {surround} audio system.
To that finish, the corporate developed DTS Digital:X, which employs digital sign processing (DSP) in an effort to supply the identical spatial cues {that a} conventional DTS:X system would supply, however over a smaller variety of audio system, even for those who’ve solely acquired two. This expertise first rolled out in soundbars, which is sensible, as they typically solely embody a separate subwoofer and perhaps a pair of satellite tv for pc audio system at most. Since then, corporations like Denon and Marantz have added help for DTS Digital:X to their receivers, whereas Sony has its personal digital {surround} soundbar that reads DTS:X and Atmos mixes.
Technically talking, “virtualized” Dolby Atmos and DTS Digital:X are very related; nonetheless, Dolby prefers to not distinguish between Dolby Atmos implementations. So far as it’s involved, Atmos is Atmos, whether or not it’s virtualized via two, three, or 5 channels, or totally baked utilizing a discrete 5.1.2 or higher speaker system.
Auro-3D
Although it’s possible you’ll not have heard of Auro-3D till now, it was on the scene nicely earlier than DTS:X or Atmos appeared. The expertise was introduced in 2006 to be used in theaters however wasn’t obtainable for house theater methods. Because of Denon and Marantz pushing it via as a firmware improve, now you can use it with your house audio system — although you must pay for it.
Regardless of obvious likeness to Dolby Atmos, Auro-3D creates a surround-sound expertise via a three-tiered sound system. A number of audio system actually showcase this sort of layered sound. We advocate eleven audio system to get probably the most out of the sound, making Auro-3D the costliest setup you possibly can recreate at house. As a result of Auro-3D often makes use of a single overhead channel, its speaker configurations aren’t optimum when used with Dolby Atmos sound.
We haven’t seen a development in reputation for Auro-3D in the USA, however contemplating its pervasive utilization in Europe and Japan, it’s solely a matter of time.
MPEG-H
MPEG-H refers to an entire household of audio and video requirements, however for {surround} sound, we’re inquisitive about a particular a part of it: the help for 3D Audio. On this regard, MPEG-H is similar to Dolby Atmos and permits builders to set an unimaginable quantity of audio objects in a 3D house. It’s additionally a particularly versatile commonplace, permitting builders to provide customers the choice to manage particular components of the sound like dialogue or selecting the place particular sounds come from. We now have a extra in-depth information to MPEG-H proper right here.
Whereas MPEG-H isn’t as widespread in North America, you will discover it on Brazilian and South Korean broadcasts, in addition to a wide range of house theater merchandise from manufacturers like Denon and Marantz. As the usual turns into extra standard, particularly for broadcasts, it might develop into a sought-after solution to watch stay TV in 3D audio.
IMAX Enhanced
Whereas it’s a more moderen commonplace, it’s additionally no shock that IMAX has its personal candidate within the house theater {surround} sound house, often known as IMAX Enhanced. IMAX Enhanced will get lots of consideration for its visible enhancements, which reformat compatibility in motion pictures and switch off all different picture optimization to make the film look extra such as you’re watching it in IMAX, even as much as increasing the side ratio.
However IMAX Enhanced additionally makes use of a part of the DTS:X codec to assist house theaters imitate IMAX Signature Sound in an IMAX theater, together with the deep bass. This commonplace is new sufficient now that it’s not more likely to make an impression on your house theater for a number of years. It’s additionally vital to notice that some content material that claims to be IMAX Enhanced doesn’t have any of the DTS:X audio enhancements, solely the visible modifications. That’s an issue for titles like Disney+’s IMAX Enhanced Marvel motion pictures.
In sum …
Whereas it might seem to be issues are getting extra difficult, studio-quality house theater sound is extra accessible than ever. Improvements in “object-based” or “3D” {surround} sound, mixed with the addition of devoted audio system to the usual 5.1 setup have upped the ante, certain — however you don’t have to be a sound engineer or audiophile to create an immersive expertise at house. A bit of little bit of analysis goes a great distance, so hold this information useful as you construct your setup and you shouldn’t have any bother determining what’s best for you. Blissful viewing/listening!

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