Volume One: The Twentieth Century is a collection of ambient sound tracks and individual sound effects for contemporary RPGs. The ambient sound tracks are full and rich - "1930s/40s Swing Club" features three minutes of crowd noise and jazz music, with laughing patrons, clinking glasses, and cigarette girls in the foreground. The "1950s Corner Gin Joint" track features the sounds of a pool match, a radio broadcast of a baseball game, and some background conversation, and the 1960s Go-Go Club, 1970s Disco, and 1990s Industrial Bar are just as full and rich. Each track clocks in at around three minutes.
Other goodies in this set include: a noisy, staticy morse code message (I'm tempted to try to translate it), calm and panicked distress calls with lots of dropouts and static, an emergency broadcast message announcing the declaration of martial law (thousands of uses!), an evil genius headquarters and mad scientist lab, a cave, a sewer, a couple of different cities, and several different types of gunfire. Most tracks seem to run around a minute and a half long, with the ambient tracks running closer to three minutes, and the sound effects (like gunfire) clocking in at less than half a minute.
Some of the background tracks don't work quite as well when looped. The Swing Club track, for example, fades in as the house band is in the middle of a song, and fades out the same way. I feel this track might have worked better if it were a bit longer, and included three complete songs (that would make the track seem less repetitious to the players if their characters are spending a lot of time in that particular scene). Some of the other tracks have a long period of silence after the fadeout, which would create a noticeable hole in the effects if it was being looped. This could be somewhat remedied by playing the tracks more quietly (at the risk of losing some of the nuances), or more technically adept gamemasters could use an audio editing program to remove the silence and make their own extended versions of the tracks.
All in all, it's a quality package for a reasonable price.
[4 of 5 Stars!]