703 vs pink for open ceiling joist treatment

Hi Everyone. Thanks in advance for the advice. I tried a search for this before posting but was unable to find anything. Forgive me if you've been over this. My new basement studio will have an open joist ceiling. I've been planning on putting 4" OC 703 with a 2" air gap between all the joists for a couple of reasons. 1) to give the illusion of a higher ceiling for tracking (I'm at 7'7" to the bottom of the joists). 2) to stop reflections off of the polished concrete floor 3) to provide some bass trapping. It's not ideal placement but I assume it's better than nothing 4) to possibly provide a small degree of isolation from the floor above. I realize this will be small. My main question is that I've had a look at bob golds absorption coefficient chart (http://www.bobgolds.com/AbsorptionCoefficients.htm) and discovered that 4" of OC 703 has very similar absorption ratings as 6" of the pink fluffy unfaced r19 OC rolls. The pink stuff will save me a ton of money. Is there any reason not to use that instead? Also, I intend to cover the bottom of the fiberglass with a very thin plastic film to avoid fiberglass fibers filtering down. Anyone have any data/experience with this and how it affects acoustics? If anyone has any general experience with ceiling absorbers I'd love to hear it. Thanks!

you could use faced insulation to trap the fibers but also consider in most locations you need to enclose the insulation behind drywall. using fire retardant cloth may meet your building inspectors requirements.

Thanks for the reply. So am I correct that 6" of the pink is roughly equivalent to 4" of 703? I'm doing it without a permit so I'm mostly just concerned with my own health. I plan on covering it with fire retardant acoustic cloth panels.

in terms of measured acoustic coefficient for a given product in a given test, yes. the pink stuff should be OK for the LF recognizing that absorption is not isolation...