With the switch to working from home during the pandemic, I was looking for something to help cut down the amount of sound coming through the door to my office. Along with a some additional items that I'll go into below, these tiles really did the trick.HOW MANY DO YOU NEED: With 24 tiles I was able to fully cover (i.e. no gaps) a standard interior door (32" x 80"), with a few tiles and some scraps to spare. I've included a picture so that you can get a sense of what that might look like.ACOUSTIC EFFECTIVENESS: These tiles significantly reduce sound at the locations they are placed, but whether they reduce sound enough for your needs will largely depend on whether you've left other ways for sound to enter your space. Most obviously, they will not be able to eliminate or reduce sound that's coming through gaps they aren't covering. If your sound is coming through a wall, covering the wall in these should significantly help. If your sound is coming from a door, as was my case, these tiles should be the first step you take in fixing the issue, but you may also want to seal the gaps around your door, depending on your needs.COLOR: I purchased the white tiles, which you can see in the attached picture. For reference, the light source in the picture is a "daylight" color LED bulb, which is a fairly cool white, the trim in the picture is painted with Snowbound SW 7004, which is a fairly stark white, and the walls are (I think) Light French Gray SW 0055, which is a very true gray (i.e. neither warm nor cool).QUALITY CONTROL: Out of the 24 tiles I received, one came with an obvious black smudge on its facing side that wouldn't clean up easily. I was able to use it for scrap pieces around the edge of the door.CUTTING: A standard box cutter, ideally with a fresh blade, was the right tool to use. From experience, scissors are the wrong tool. For my part, I simply used a pencil to trace the lines I wanted to cut, then made a series of successively deeper cuts with the box cutter until I was through. It was surprisingly easy. I was even able to mount it cleanly around the door handle with some careful measuring and removing the fitting so that I could use it to trace the circle.MOUNTING: Based on recommendations in various comments, I opted for Scotch-Mount Indoor Double-Sided Mounting Tape 314H-MED, 1 in x 125 in. foam mounting tape, figuring that the foam cells and the air gap it creates between the door and tile would aid in sound isolation. I cut off 5 squares from the roll for most of the tiles (four in the corners and one in the middle), each a bit under 1" in size, and I still had plenty of tape left at the end. None of the tiles have fallen off after 2 months of opening and closing the door, though I have noticed that a few of the scrap pieces along the edge where I used less tape have become a bit loose, so I may need to add some more. Link: https://amazon.com/gp/product/B0007P5G8YADDITIONAL MATERIALS: After getting the tiles up on my office door, I couldn't hear typical sounds coming through the tiles themselves, but I could hear sounds coming through the gaps between the door and the door jamb or floor. After doing some research, neoprene seemed like a good choice, so I picked up a few rolls of White Foam Weather Stripping in different sizes to fit the variously-sized gaps around my office door. Make sure to measure each of the dimensions of your gaps carefully, since neoprene doesn't compress much and that adhesive WILL take paint off your door if you try to remove it later (e.g. I had to remove the 1/8" thickness tape I put on the hinge side because it kept the door from closing). Even so, I HIGHLY recommend it if you want additional sound isolation for your door. In my case, I added it to the top, left, and bottom sides of the door as it appears in the attached picture. Link: https://amazon.com/gp/product/B08HVJ2KZGRESULTS: With both the tiles and tape in place, my office door transformed into an airlock. It feels like I'm sealing myself off from the world whenever that door closes, making a sucking sort of sound as it does so. It's EERILY quiet. My wife has literally been watching movies at theater volume in the room across the hallway from my office, and I had no clue until I opened the door. I can usually hear when she knocks at the door, but I have to practically shout "come in" for her to be able to hear my response.FINAL WORD: If you're wanting to get sound isolation for a door, start with these, cover your door while leaving no gaps, and then see how it is for you. If you need additional isolation, look into the tape I mentioned above.-------------------EDIT (2023-05-16): Following up two years later to provide notes on longer-term use. In general, everything has held up remarkably well. The solution I laid out two years ago with the tiles and neoprene weather stripping has proven every bit as effective as I had hoped.A few of the tiles near the latch-side of the door have become discolored with dirt and oils from hands touching them over the last few years. I wouldn't necessarily change anything in response to that, but it's something to be aware of if you're purchasing light-colored tiles for use on a surface that will have frequent touch.The one thing I would change is how I taped them up. The adhesive doesn't really penetrate well into the fabric-like surface of the tiles, so it's a bit easier than I'd like to knock them off by brushing up against them. They're easy enough to put back on, and they'll generally stay in place so long as they aren't disturbed again, but if I was starting from scratch today I'd either find an alternative tape that works better with fabric or I'd use 2-3x the pieces of tape in the hope that it would prove more effective.