What is Dolby Atmos and why should you care?
Dolby Atmos is commonly known from cinema and you regularly hear the words 360 sound or immersive when talking about Dolby Atmos. As the format adds support for ceiling speakers, the mixer are now able to put the listener inside the action, not just listening to it. However, even though the celling channels are intriguing, there are more to Dolby Atmos that makes it the first format capable of challenging stereo.
What is Dolby Atmos?
Dolby Atmos is in its core base a surround sound technology made by Dolby Laboratories. The format has two sides that are equally fascinating - the experience and the technical side.
the experience.
When listening to Dolby Atmos on speakers, this format immerses you into the action of the content you are listening to, may it be a song or a full blown Hollywood movie. The beauty of the format is that it adapts to the speakers you are listening to and automatically creates a personalised mix, made just for the speaker configuration you are playing the content back on.
Today there are a big variety of speakers that can play back and adapt to Dolby Atmos content. The format can be scaled up and down, from smart speakers to a huge cinema. To give you a sense of whats available, here goes a list of the most common playback systems:
Soundbars.
Most new soundbars utilities Dolby Atmos support for upward firing speakers. This makes it possible for speakers like the one on the picture, Sennheiser Ambeo to fill the room with sound and enlarge the sound scape with sounds from above and all around you.
Smart speakers.
Like the soundbars, more and more smart speakers adds support for Dolby Atmos and has upward firing drivers that create the sense height and makes the music or film feel more natural and realistic.
Home theatre.
If you are feeling ambitious, installing speakers in your celling and surrounding yourself with a configuration like the picture, 7.1.4 (7 speakers around you, 1 subwoofer and 4 in the ceiling) gives you the most impactful and precise experience and you will feel like you are right in the action.
Cinema.
Dolby Atmos can even be scaled up to huge cinemas allowing a big audience to get immersed in the movie or music.
Headphones.
When headphones are used to play back Dolby Atmos content, the device renders a binaural mix that pushes the limits of your ordinary headphones and gives you a wider image than ever before. More on how this is done further down.
Stereo vs Binaural
Whatever system you choose, Dolby Atmos makes sure that you get the best possible experience for this given setup. In short terms, it will adapt to your gear. This brings me to the technical side of Dolby Atmos - what is the difference between stereo, regular surround and Dolby Atmos?
Channel vs Object based sound.
Talking about Dolby Atmos can easily become technical and hard to grasp and to understand the technology we have to make one thing clear, the difference between channel based and Object Based sound.
The most common formats today are channel based. For example, when listening to Spotify with your earbuds, you get fed two channels, the left and the right. To create a stereo image you adjust how much of each sound should be sent to each channel.
For example, if you send the same amount of volume to the left and the right channel, the sound will appear as if it is being played right in the middle of the sound field: This is called phantom center. If you want the sound to come from the right side of the image you just lower the amount of volume being fed to the left channel. This image to the right shows channel based panning in a graphic way.
The problem with channel based sound is that is is fixed into the number of channels that it is mixed in. This is called channel dependent sound and means that it cannot be converted into anything else stereo.
The same logic applies to regular surround, like 5.1. The difference there is just the number of predetermined channels that it is mixed in. In a channel based environment there no more information
Challenging this old school technology is Object Based Sound.
When mixing or creating in an object based environment, you place the sounds in a three dimensional room where you ideally want them to be played back, instead of just changing the volume of the predetermined channels. Each sound or instrument gets its own XYZ coordinates and can be automated to move throughout the song or film.
These coordinates, together with the audio files gets burnt in to the master file follows the song or movie all the way to the end user, the listener.
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