simple tips for soundproofing a room
An airplane under test in a giant anechoic chamber.
If you just want to make your home a little quieter, you won't want to go to extreme lengths like building yourself an anechoic chamber or a room within a room; if all you're doing is the crossword or the knitting, you probably don't need a padded cell! Making an ordinary room quieter involves a two-pronged attack on noise through a combination of noise reduction and noise absorption.
Photo: Some people go to extreme lengths to soundproof rooms, but that doesn't mean you have to! Here's the world's biggest anechoic chamber at Edwards Air Force Base, California. The blue triangles you can see are energy-absorbing foam wedges similar to the ones in our upper pictures. Photo by Thomas Powell courtesy of U.S. Air Force.
Noise reduction
The first, obvious step is to tackle the routes by which noise enters your room. Doors and windows are likely your biggest problem, so check those out first: make sure they're shut tight and locked, check the seals, install draftproofing or caulking, and use draft excluders. Double or triple glazing can be a big help if your problem is something like airport or highway noise, but make sure there's a big air gap and proper seals. Do you have an open chimney you're not using? If it's safe to do so, block it up. If soundproofing is your mission, you really need to go around your room (or rooms) systematically, identifying every possible access point where sound can get in and doing whatever you can to block that path. But in your quest to block out sound, don't forget that blocking your ears (with earplugs) may be far more effective—especially if the noise is only a temporary nuisance.
Noise absorption
Once you've reduced incoming sound as much as you can, you could try altering the interior of your room so sound waves are absorbed rather than reflected by materials inside. Carpets work better than wooden floors, but rugs can work a treat too. Soft furnishings such as wall hangings (tapestries or blankets), sofas and cushions soak up sound very effectively (that's why rooms sound so different when you've emptied them to decorate or move house). Curtains are good at absorbing sounds from either inside or outside, but make sure they're dense and heavy, reach right down to the floor, and seal well all round. Thermal curtains linings and blackout curtains (designed to stop heat loss and make rooms darker at night) can significantly improve sound insulation for problems like traffic and street noise.
Further Reading
On this website
Sound-level (decibel) meters
Energy
Sound
Ultrasound