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Atmos-enabled speakers are the convenience-over-performance, and therefore not surprisingly the most popular, method of adding height channels to your system. The best effect is achieved by mounting actual height speakers overhead. However, that solution is often unpalatable, so bouncing the higher frequencies of the height signals off the ceiling provides a reasonable sense of elevation in a practical manner. Dolby Labs tells us that Atmos-enabled speakers work best in rooms with a flat, hard ceiling at a height of 8 to 9 feet, though up to 14 is acceptable. Light fixtures, moldings, and vents probably won’t interfere much with the ceiling bounce; vaulted or angled ceilings and acoustic treatments will.”