If you have a completed ceiling already that has an access blow the Owens Corning product in it.

The above mentioned R-11 with R-19 on top works but is a major PITA to install...

When your done you've done twice the labor and still only have an R-30...

Using the blown in you can install as much or as little as you want without all of the crawling around on top of the truss's... twocents

https://www.lowes.com/pd/Owens-Corning-AttiCat-R-19-Blown-In-Insulation-Sound-Barrier/50370322


...FAFO...