Audio can be output in a number of ways, starting with “mono” signals. Mono simply means one channel, with the entire sound signal folded into a single output. Examples of devices that use mono signals include radios, older computers and some club and PA systems. Essentially, anything with a single speaker is mono.
The most common output format used in TVs, computer systems, mobile devices, headphones, earbuds and home audio systems today has two channels: left and right. This produces a wider audio range than mono and allows more creative sound expression by positioning elements on one side or the other or panning sounds from one speaker to the next, creating the illusion of movement. Stereo sound also creates a phantom centre, where it seems like the sound is coming from between the speakers, but it’s actually coming from the left and right channels simultaneously.
Adding extra speakers that surround the listener creates an even greater sense of direction, space and depth. The most common surround sound configuration is a 5.1 set-up, in which a centre speaker is added to the main left and right speakers, plus rear left and rear right surround speakers, making five main speakers. The .1 refers to a bass speaker or subwoofer for handling low frequencies. In 7.1 configurations, two more side speakers are added.
Dolby Atmos builds even further on the capabilities of surround sound by adding height channels to the mix. Like surround sound, there is a bed of left, right, centre and rear speakers, but there are also additional speakers, either positioned in the ceiling firing down, or in the form of soundbars and other speakers below firing upwards to reflect sound from the ceiling. As a result, Dolby Atmos creates the most three-dimensional soundscape possible. In Dolby Atmos speaker systems, the set-up is described as 5.1.2, 7.1.2 or 7.1.4, with the final number representing two or four height channels.
The way audio content is mixed in Dolby Atmos broadcast also enhances the immersive effect. Dolby Atmos mixes can feature up to 118 audio objects that audio mixers and sound designers can place anywhere in 3D space, roaming from front to back, floor to ceiling and anywhere in between. This creates nearly unlimited possibilities for movement and depth, and the most accurate reproduction of sound as our ears perceive it in the real world. This is the real power of Dolby Atmos, and why it’s so different from previous audio technologies.
To experience Dolby Atmos at home, you’ll need a few essential pieces of equipment. This starts at the source of the signal, usually the TV, which should have an HDMI eARC (enhanced Audio Return Channel) output to your soundbar or receiver, which should also have an HDMI eARC connection and Dolby Atmos capability. If you use a source with a standard HDMI ARC connection, you’ll still hear sound, but it will be limited by data bandwidth to the stereo or surround sound version of the signal only, not the Dolby Atmos mix.
Using a soundbar is by far the easiest way to experience Dolby Atmos and is much simpler than installing a receiver and speaker system around the room or in the ceiling. The newest generation of soundbars, which includes models such as the Bose Smart Soundbar 900 and the Bose Smart Soundbar 600, have full Dolby Atmos capability, with nine internal speakers, including two upward-firing speakers to reproduce the Dolby Atmos height channels. Adding a pair of Bose Surround Speakers 700, or a Bose Bass Module 700 subwoofer will add some additional immersion, especially on the low end. The Bose Smart Soundbars also make the set-up easy, with a single HDMI eARC port enabling connection to a Dolby Atmos-enabled source.