"HOME VS. CINEMA - STANDARDS
Various standards and recommendations exist for the different applications of multi-channel sound in different environments such as cinema, broadcast and home use. The two most use recommendations are the ITU-R BS.775 standard for multi-channel sound from the International Telecommunications Union (an international standardization body) and the THX recommendations for cinema (a commercial organisation). The ITU recommendation is the most used standard for 5.1 Surround Sound in broadcast and home cinema applications. One of the recommendations is to install the speakers of the Surround system at “ear-level” (typically between 90 and 120cm height). This has the big advantage that most sound sources (with their origin at ear level) can be reproduced as in real life. Sounds that move from the front channels to the surround channels (e.g. cars, bikes passing by, etc..) can be positioned where we expect them. A good audio-visual coherence allows for our brain to believe that the sound we experience relates to what is seen on screen., increasing the immersive experience.
In practice, regular 5.1 Surround systems suffer from a ‘hole’ between front and back speakers, due to the way the human hearing system works, making the sound jump from front to back. When adding a quadraphonic Height layer, like in Auro 9.1, this effect is dramatically reduced, eliminating the need for 7.1 surround as a basic layer in order to solve that issue. Installing a 7.1 Surround system is also not practical in most home cinemas , whereas 5.1 is much easier. There is also often place above the corner speakers of a 5.1 system to add Auro-3D’s unique Height Layer, making it a practical solution for real 3D Immersive Sound.
The THX 5.1 standard became famous in the professional cinema industry and was also adopted in high-end home cinemas. But there is a big difference between a sound system designed for a large theater with hundreds of seats and a system for a home theater with 10 to 20 seats. In order to create good dispersion of the sound in a cinema theater, the speakers need to be installed higher than ear-level (THX recommendation is based on a 15° elevation angle). The same is true for the screen channels although most of the source sounds at screen have their apparent origin below the middle of the screen. This is not the case in a small room where sound can be equally spread across the room without the need of elevating the speakers that high. Installing the surrounds higher than ear-level might make sense for 5.1 or 7.1 Surround sound systems because not all sounds originate from ear-level and a compromise can be made by elevating them up to 15° as done in large theaters. But when installing additional layers to reproduce the Height information, it is much better to install the ear-level layer as defined in the ITU recommendations.
Dolby Atmos’ speaker installation for cinemas is not based on the existing THX 5.1 surround standard. The surround speakers are positioned substantially higher, much closer to each other and with completely different orientation towards approximately the middle of the room. This results in a different sound experience than coming from a standard 5.1 system. "
Kilde:
https://www.stormaudio.com/media/co...s_setup_20160219__085700400_1344_13062017.pdf
