Actually, yes
Actually, it does help. It acts to absorb the reflections and quiets the room. A textured ceiling acts more like an anechoic chamber than a flat ceiling does, unless you are using acoustical tiles. A smooth flat surface transfers sound (and light) much more efficiently than a textured surface. The greater the texture, the higher the absorbtion. That's why in an anechoic chamber, the foam pads have "waves" instead of being flat. I was just in an anechoic chamber at COSI (Center of Science and Industry) in downtown Columbus, OH. It's so dead silent in an anechoic chamber, your ears feel like they are about to pop.