What is Dolby Atmos?

Mono -> Stereo -> Surround -> Immersive

Mono - 1D Spot

In the early attempts back in 1876 by Alexander Graham Bell, audio/music/sound was (re-)produced by only a single speaker, a cone without electrical amplification. It played back a single audio source, a single audio channel.

Stereo - 1D Line

The invention of stereophonic recording and reproduction via two (amplified) speakers (credited to Alan Blumlein in 1930) made it possible to create a 1- dimensional sound field so the listener could locate a signal between (and outside) the two speakers via the known phenomena, Phantom Source.

Surround - 2D

Although Ray Dolby is often credited as the inventor of the surround sound in the 1970s, there were earlier implementation like the 1940s Disney movie “Fantasia”. The idea was to have sound not only coming from the front of the listener, but also from the side and the back. Although it means that the listener is “surrounded” by sound, it is still a 2-dimensional sound field.

Immersive - 3D

The big difference with Immersive Sound is that it adds a third dimension to the sound field. This way, sound is also coming from speakers above the listeners in addition to the surround speakers on their ear-level. Because the listener is “immersed” in a 3-dimensional sound field, “Immersive Audio” is also referred to as 3D Audio.

Gray Area

Mono vs. Stereo
Speaker vs. Channel
Surround vs. Immersive
Immersive Audio
Ambisonics

Mono vs. Stereo

While Stereo often implies two speakers and Mono just one speaker, a stereo speaker playback is considered mono if both channels are fully correlated (playing the same signal).

Speaker vs. Channel

The existence of multiple speakers placed around the listener doesn’t mean that you are listening to “Surround Sound”, it only means that you are “surrounded” by speakers. If 20 speakers around you all playback the same signal, then you are technically listening to a Mono signal (1 audio channel) coming from multiple speakers, also referred to “Super-Mono”. All those individual speakers have to be able to play back individual (different) channels to get the actual surround experience.

Surround vs. Immersive

These two terms can also lead to some miscommunication when their understanding is different (and it often is). Technically, when you listen to Immersive Audio, you are “surrounded” by sound but you are not listening to “Surround Sound” which is used to describe configurations where all speakers are on ear-level plus the sub woofer (i.e. 5.1 or 7.1). That creates only a 2-dimensional sound.

Immersive Audio

The term Immersive Audio can be confusing all by itself, because there are many different technologies with different meanings that could describe the same or similar experience. The most-often used terms are Immersive Audio and 3D Audio, but also 360 Audio or Spatial Audio or whatever the marketing department of a company dreams up at the time. Some people us the term Surround Sound even for Immersive Sound, which is a bit of a sloppy use of terminology.

Ambisonics

Keep in mind that the term Ambisonics that is often heard in the context of Immersive Audio is the name of a special recording of a full-sphere immersive sound format.

Key aspects of Dolby Atmos

Workflow
Immersive Sound
Object-based Format
Speaker Rendering
Speaker Virtualization
Binaural Rendering
Sing Format Serves It All
Dolby Atmos Everywhere

Workflow

Your DAW:
Dolby Atmos Renderer:
3D Panner:
Separate Pan Data Transmission:

Object Audio Renderer (OAR):
Dolby Atmos Master File:

Open Master File:
Delivery files

Encoded Bitstream Files
Consumer Playback

Three tasks of the Dolby Atmos Renderer

Mixing
Recording
Exporting

Immersive Sound

Height Speakers

How many speakers?

Object-based Format

Channel-based mixing

Object-based mixing

Tracks in a DAW are assigned to Objects
Position the signal in 3D space
This positional data is stored as metadata (Object Audio Metadata) with the file
Playback device uses the XYZ information to reproduce the mix on a given set of speakers. AKA Rendering with the Object Audio Renderer

Speaker Rendering

Let’s assume a movie is mixed on a big dubbing stage with a big Dolby Atmos configuration using its maximum of 64 speaker channels.
Playing back the mix in a big theater with the same 64 big speaker setup would play back that mix perfectly fine. If that mix is played back in a smaller multiplex theater with only 20 speakers, then the Dolby Atmos systems “renders” the 64 speakers to 20 speaker to get the same immersive experience. Let’s say a signal that played in the front height speakers and then the back height speakers now plays in the single height speaker if there is only one height speaker instead of front/back.
If that mix is played on an even smaller speaker setup, then Dolby Atmos “renders” that mix so the immersive sound experience is replicated as close as possible on the available speakers.
That “Speaker Rendering” capability is built into any home Dolby Atmos playback device. This could be an expensive home theater system, an AVR (Audio Video Receiver) in your living room, or a computer, tablet, and even smart phone.

Not a Downmix!

This Speaker Rendering process is kind of an “adaptive” downmix procedure, but much more intelligent and more capable because Dolby Atmos is Object-based and not Channel-based like conventional surround formats.

Speaker Virtualization

Speaker Rendering: Using the panning data to route the audio signal to the speaker layout of the given room.
Speaker Virtualization: Alternative to multi-speaker setups
- Soundbars - Samsung HW-Q90R
- Smart Speakers - Amazon Echo Studio
- Computers
- Tablets and smart phones
- Binaural Rendering

Single format

Atmos Everywhere?

Cinema
Home Theater
Broadcast - sports events etc.
Games - binaural rendering, could use head-tracking. competes with Ambisonics
Cars - Lucid Air
Music
Live Events

DAW support

Pro tools - the standard, tightest integration with the Dolby Atmos Renderer app.
Nuendo - the first DAW with Dolby Atmos Renderer built-into the DAW.
Logic Pro - limited support see Next Week
DaVinci, Pyramix
Other DAWs - can mix in Dolby Atmos using the Dolby Atmos Music Panner together with the Dolby Atmos Production Suite.

Choices for streaming Atmos music

Tidal
Amazon Music HD
Apple Music
Spotify
Deezer - “Sony 360 Reality Audio”