Audio and speakers
Height channels
Speakers mounted in or on the ceiling, or upward-firing modules, that reproduce the overhead layer in Dolby Atmos and DTS:X.
Height channels add a layer of speakers above ear level. They can be in-ceiling, on-ceiling, high on the front wall, or upward-firing modules that bounce sound off the ceiling. They are the third digit in a layout such as 5.1.4.
They provide the overhead dimension object-based formats were designed for: rain, aircraft, and the sense of a room having a ceiling. Two well placed heights add more than two extra ear-level surrounds, and four make overhead motion coherent front to back.
Dolby recommends top front and top rear pairs at roughly 45 degrees elevation from the main seat, with an acceptable range of about 30 to 55 degrees. Upward-firing modules need a flat, reflective ceiling of about 8 to 12 feet; vaulted or acoustic-tile ceilings defeat them.
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