How to seal the air gap between the door and floor\doorpost

Convering my Bedroom into a decent sounding Bedroom studio. The process involves two stages when stage number 1 is done. 1.Acoustic treatment which consists of 4 corner traps,1 could,8 panels all based on Broadband design,thinkness of Isolation ranges from 10cm on the panels and could to 20 cm on the corners,filled with 42kg\m3 rockwool 2.Basic isolation Room type: Bedroom Problem: The main issue of sound leaking into to the studio from the rest of the house is thru the cracks between the upgraded standart wooden door (originaly 3 cm MDF,thickened externaly with additional 4 cm of Rockwool) and the floor\doorpost. Please recommend methods\matirials for sealing that air gap. Tomer.

Adding an extra layer of mineral wool to a door is not going to do ANYTHING for isolation. My best recomendation would be to get Rod Gervais' book (see top of forum) as he goes into this very issue in some depth. In a nutshell, you need mass, mass, and more mass. I hope you're not saying that your entire door is just 3/4" MDF! You need a lot more than that. Your big problem is the seals around the door. The door needs to be air tight all the way around and the joint between the drywall and the door frame needs to be calked as well. You should get drop-down seals for the bottom of the door. The three other edges are best addressed in Rod's book. len