Author : MD TAREQ HASSAN | Updated : 2022/08/17

Understanding Object-based Surround Sound

Object-based surround sound technologies try to encode sound of each object in the scene seperately so that when decoded and played in compatible audio device (i.e. a soundbar), it give more realistic immersive sound experience.

Let’s say we have a movie scene in which there are 3 objects - a helicopter flying on top, a person talking on left and a vihecle passing by on right side. If the audio is encoded as Dolby Atmos, sound of each of these objects (helicopter, person and vihecle) will be encoded seperately and will be reproduced seperately. Therefore, listening experience will be realistic and immersive.

Object-based Surround Sound Technologies:

Understanding Dolby Audio

Dolby Laboratories, Inc (shortened to Dolby Labs and known simply as Dolby)

Dolby Audio Formats

Dolby Digital (DD)

Dolby Digital Plus

Dolby TrueHD

Dolby Digital Plus vs Dolby TrueHD

Feature Dolby Digital Plus Dolby TrueHD
Audio Channels 6 8
Speaker Configuration 5.1 7.1
Bandwidth 6 mbps 18 mbps max.
Lossy or lossless lossy lossless
HDMI port ARC or eARC eARC

What is Dolby Atmos?

Dolby Atmos is a 3D surround sound technology that allows sounds to be placed anywhere in a 3D environment. Atmos is not a audio format, rather it is metadata about audio to encode and decode object-base surround sound. An Atmos compatible audio device (i.e. a soundbar, in my case Sony HT-X8500) can recieve Atmos audio encoded as Dolby Digital Plus or Dolby TrueHD format and then process Atmos data (metadata) to reproduce object-based sorround sound mentioned that it does not matter how many physical speakers the audio device have (2.1 in case of my Sony HT-X8500).

Atmos compatible formats”

Playing Dolby Atmos to Soundbar

To play Dolby Atmos, we need HDMI ARC or HDMI eARC:

See: how to play dolby atmos and dtsx audio in a soundbar