Do you think these would help?
For "soundproofing a door"? No! That's just a thin absorption blanket. It might help to
treat the room slightly, but will do practically nothing to
isolate it ("soundproof"). Contrary to popular belief, you cannot soundproof a room with acoustic absorption. (Or at least, not with a reasonable thickness: If you make it many feet thick, then it might work...)
The ONLY practical way to stop sound is with mass. In reality there are three ways of stopping sound:
1) Use a barrier that is infinitely rigid. If it is so rigid that it cannot move at all, then it cannot transmit sound. Unfortunately, there is no such material: Even high density concrete is not totally rigid.
2) Use a barrier that is infinitely massive. If it is so heavy that nothing can move it, then it cannot transmit sound. Once again, no such substance exists.
3) Remove everything that can transmit acoustic energy, even the air: in other words, create a total vacuum.
That's it. There are no other options. All forms of isolation ("soundproofing") work on one of these three principles of physics. There are no magical materials, no incantations involving goat bones and bat wings. Just mass, rigidity and vacuum. Yes, you can combine two leaves of mass separate by an air gap to create a tuned isolation wall, with increased effectiveness for some frequencies, but that is still based on mass.
Of those three, the only PRACTICAL one for use in home studios, is mass. It turns out that some very massive materials are also reasonably rigid, so that helps too, but your number one best friend in isolation is mass.
Notice that "absorption" is not on the list? You can't stop sound by trying to absorb it for the same reason you can't stop water coming out your kitchen tap by putting a sponge across the end: sound still gets through, even though some is absorbed on the way.
Mass means "weight". Heavy. Dense. Things like plywood, MDF, drywall, concrete, steel plate, thick glass, fibercement, etc. Those are dense, heavy, rigid materials that work well to isolate. Those absorption blankets are none of the above. Look at the lab report: the lab tested them for "acoustic absorption", not "acoustic isolation"! The lab knows what they are useful for, even though the manufacturer seems to be promoting them for a different purpose. But they are absorption blankets, pure and simple, with practically no use in isolation.
So what is absorption used for then, if not for isolation?
For treatment! Isolating a room ("soundproofing" it) implies that you stopped the sound from getting out. In other words, you kept the sound INSIDE the room! so you made the room sound bad: the sound is now bouncing around inside, with nowhere to go, and you have a very reverberant, resonant, "echoey" place. You fix that by treating the room, usually with large amounts of absorption. Just like a sponge is no use for stopping water coming out the tap, but is great for mopping up water that spilled where you didn't want it, so too absorption is no use for stopping sound getting out, but great for absorbing sound that "spilled" around the room, where you don't want it.
So you could use those blankets as part of the treatment of your room, once you have it isolated, but even then I wouldn't use those: Look at the specs on page 6 of the lab report! Very strangely, those blankets have peak absorption at around 1 kHz, ant it rolls of rapidly below that to NEGATIVE absorption
at 100 Hz!, and also rolls off towards the high end. Not very useful, acoustically. And the lab that did the tests actually gave them a break by hanging the blankets in a very favorable manner, held 3" away from the wall: that's probably why they get reasonable results in the mid range. If they would have hung the blankets as recommended by the manufacturer, right AGAINST the wall, the results would not have been as good as that.
Small rooms have problems in the LOW frequencies, not so much in the mid range, so those blankets would not be much use for that.
For treating small rooms it's hard to find better low-cost treatment than plain old fiberglass insulation! The type you can buy in Home Depot for insulating your house walls. Just buy some 4" panels of semi-rigid Owens Corning 703, which has vastly superior acoustic characteristics, and put those diagonally across the corners of the room, floor to ceiling, as well as against a couple of the walls. There's nothing better than that, at low cost.
But that's treatment. To isolate your door, you need to add mass. A sheet of thick MDF, plywood, OSB or even drywall will help a lot. Replacing the door with a solid core door would help even more. Doing both (solid core plus MDF) would be even better. But whichever you do, you'll need to replace the hinges too, as normal hinges are not designed to take the weight of a a heavy acoustic door. And not matter which one you do, you still need to get those seals done! Two complete, independent seals, around all for edges of the door, is the minimum for good isolation. If there is a keyhole then you even need to seal that up. There can be no gaps at all.
- Stuart -
