My friend has built a separate building to practice/record in and is having some trouble with sound leaking outside from the drum kit.
Here is a quick sketch done in paint (no need to mock the paint skills
Obviously the sides aren't to scale and the circle in the corner represents the kit and the arrow the direction which the bass drum is facing.
The room has a solid metre deep concrete floor then carpeted, the walls are made from concrete block outsde; thermal/acoustic insulation; acoustic block inside (lighter than a breeze block); inside lined with insulated board (plaster board with fitted hard insulation on the back side); then carpeted walls.
The ceiling is external roof tiles; insulation (fiberglass); plasterboard (12m); compressed wood (25mm); secondary set of joists - (sloped 2ft-7in deep cavity filled with more compressed fiberglass); then more of the plasterboard with insulated backing.
There are no air bricks etc. Both doors are solid panel UVPC double glazed.
With drums being played, using a meter, the db reading in the room was 120db and standing outside the building it was no more than 63db.
As the building has matured, (it is three years old) it seems to be louder outside than before, with bleed from snare and toms.
Any suggestions as to what can be done to help reduce the noise heard outside the building? Really not sure where to start.
Thanks in advance and sorry for the long post.