How did it get in? Probably the same way that you did, through the door. How can you stop, or at least reduce, the noise? You can wear noise-canceling headphones, sure, but then you might not hear what you want to hear. Soundproofing a door can be accomplished by a low-tech hack or a fairly involved procedure and can be inexpensive or pricey, with a range of options in between.

How Does Sound Travel Through a Door?

Sound is an energy that travels through a medium (air, water, glass, wood, etc.) by vibration. The particles in a medium nearest the source bang into the adjacent particles, which bang into the next ones, and pretty soon you have a vibration that creates sound. The greater the density of the particles, the less the sound can move. It makes sense, then, that sound travels more easily through the air, rather than through a brick wall. In an enclosed room, the less dense perimeter areas are typically the windows and especially the doors, mainly because they have air gaps.

DIY Ways to Soundproof a Door

Method 1: Seal the gaps

Most interior doors, unlike those on the exterior, are not weatherstripped. There’s always a gap below the door and one that runs up the sides and over the top. By sealing these gaps, you will diminish the sound coming through. An easy and inexpensive method is to buy adhesive-backed, flexible foam weatherstripping. It’s available in various thicknesses and widths. Tools and materials needed:

Utility knife Screwdriver (manual or cordless) Hacksaw Adhesive-backed, flexible foam weatherstripping Aluminum and vinyl door sweep (that’s at least as long as your door is wide)

Steps: Alternatively, there are ready-to-install kits made to reduce sound transmission that consists of neoprene seals mounted onto aluminum tracks. Prices start around $250 for a standard kit. Here’s another alternative to weatherstripping that’s in keeping with the original look of the door: if there’s a large gap under the door, you could add a thicker threshold. You’ll still have a gap, but it will be smaller and so will allow in less sound. You’ll have to remove the existing threshold with a flatbar. If you’re careful to remove it one piece, you can use the original as a template for the new threshold.
Gaps in the trim that’s applied to the door jamb can let sound in too, although probably to a lesser extent. To do a thorough soundproofing job, run a bead of caulk wherever there’s a gap.

Method 2: Increase the mass of the door

Sound can penetrate solid objects. The greater the mass of the object, the less the sound will penetrate. If the door has a hollow core, you could replace it with a solid door—that is, if you want to make that investment. On the cheaper end of the cost spectrum, you can increase the mass of the door by hanging a thick blanket or carpet on it—an easy but temporary fix. Tools and materials needed:

Utility knife Straight edge Caulk gun Construction adhesive Screws Screwdriver Roll of mass-loaded vinyl

If you’re not picky about the appearance of the door, you could screw a similarly-sized piece of plywood to it; just be sure to leave enough of a gap around the door so that the plywood doesn’t interfere with the door’s operation If you really want to get serious without replacing the door, you can get sound-reduction mats made especially to be hung on doors. These are the most effective at slowing the transmission of sound waves, but they don’t come cheap. A sound barrier custom made for your door is one option.
A slightly less expensive option is to make your own barrier from a material called mass-loaded vinyl. Resembling a rubbery sheet of lead, it’s available in different thicknesses; the thicker (and heavier) the material, the greater the sound reduction. It’s only available in rolls, so if you’re only soundproofing one door, you’ll have plenty of leftovers. Steps: