Sound absorbing materials in the receiving room (his dorm room) can help lower the apparent level a bit in rooms that are already reverberant. The unwanted sound enters the room and bounces around a bit, which makes it sound louder. If you make the walls sound absorbing, it will reduce the amount of time the sound will be bouncing back and forth and it will sound softer.

Dorm rooms, however, are so small that they have very low reverberation times (which depends on the total volume and total absorption of the room). Adding more absorption is unlikely to lower that time very much - it may not even be audible. Therefore, it won't do much to help.

Also, most affordable wall treatments like those used in recording studios are totally incorrect for a dormitory, which is a completely different occupancy classification under the building code and must be much more fireproof. Foam and most carpets burn really well. No one cares if you burn down your own home studio - but in an multi-story residential or assembly space ends up with the Station Nightclub Fire.

You are right about blocking the sound getting through. Sealing the door and windows with a heavy material could help stop sound leaks - places where the vibrating air gets in. A rug in his room won't help much, but one in his upstairs neighbors room could help soften impact noise transmitted through the structure.

The only thing "soundproof foam" is good for is burning down the building and killing everyone in it. There is no such thing as "soundproof foam."

There are basically two ways airborne sound travels between two rooms: 1) air leaks between the rooms. 2) through a mechanism where the sound wiggles the wall surface on one side, which wiggles the surface on the other side and re-transmits the sound back into the air.

You can stop air leaks with attention to detail during construction - the partitions should go all the way up to the ceiling, and the floor and ceiling joints should be caulked. The only way to stop the second problem is making the wall more difficult to wiggle - or increasing it's mass. Most modern dormitories have moved away from concrete and concrete block construction which is much better at stopping sound to a gypsum wall board on metal stud construction, which is lighter and therefore transmits sound much better.

Unless you want to pour a new 6" concrete wall or line the room in thick lead, you are unlikely to be able to stop the sound transmission. Having maintenance seal the door and windows better may help if there is a leak problem. You can tell by listening around the door. If the sound is much louder near the bottom of the door than elsewhere in the room, you've found the leak.

The best way to approach this problem is to go to audiologist and get fitted for custom earplugs. They will make a mold of your ear and send it to a company like http://www.etymotic.com/hp/erme.html. You can select the filter up to a maximum of -25dB over a much more even bandwidth than cheap earplugs. It will likely solve the problem without introducing masking noise willy-nilly.

That being said, a loudspeaker playing white or pink noise could mask the problem, if you don't mind listening to it. I dislike constant noise, but that would be up to you.

If you're hearing "thumping" of footsteps or feeling the noise problem, that's a different ballgame: structure borne transmission. Buy your upstairs neighbors a thick rug so they don't impact the floor as hard or replace the ceiling with something more rigid...

I'm not sure if you're saying that the Minidisc couldn't be slot loaded - it could- or that it didn't take off in cars. Minidiscs were used heavily by the theater and pro audio industries for years (2010 is when I saw the last Minidisc player in theater racks) because they were so much tougher than a CD and could be edited on the player itself. CD Players and CDs can't take much abuse. Most of the pro audio playback is now solid state devices (for people who can afford it) or laptops (for lower budget minded folks).

Most wireless microphones operate in the "white space" frequency ranges. The FCC pushed wireless users out of the 698-806 MHz a couple years ago and caused havoc in the theater and concert industries - the small theater I worked for spent over thirty thousand dollars replacing their wireless mics, because it is now illegal to buy, sell, or use a 700 MHz microphone. I can't imagine what it will be like if they take away all the spectrum. It's hard enough as is to do frequency coordination for twenty or thirty mics that are used in larger productions. More info here: http://www.shure.com/americas/news-events/spectrum-issues/white-spaces/index.htm

It on the front page of the New York Times...

I work in a theater. We will have to spend between $6,000 and $10,000 to replace wireless microphones in the 700 MHz range, and there's no guarantee the new ones will work anymore, due to interference. If the deadline was extended, we would be able to use the old microphones for the last show of the year and wait to see what happens during the summer, which is an off season. I think that DTV is good in the long-term, but they could have done it without screwing over wireless microphone users (a high profile industry-- think of all the rock stars and football stadiums).

MiniDisc is often used in theater because you can edit tracks on the disc without a computer. I use it to make back-up recordings and play sound effects simply because it's easier to use than CDs.