Intermission, also called by players as Aftermath or The Life Beneath It All, was the song that Trent Reznor and his musical project Nine Inch Nails did compose for Quake (DOS) (and consequently for Quake (SAT)). It is a windy, rhythmic footsteps score having additional guitar noises which has a few to scare a player with (unlike some other parts, as sample The Necropolis or Ziggurat Vertigo). The song is usually used for intermission screens, hence we get an unofficial title.
The title comes from the game location. As stated above, some Internet sources give it some weird names for aesthetical reasons. The song is track number three on the disc.
Games
Quake (DOS)
The song plays between levels when you see the level results tally. It begins with a strange sound reminding of a portal or a Slipgate (however, Slipgates are usually built between the start map and each first level of episodes but the tune is the same for all situations).
Quake (SAT)
In the Sega Saturn release, Intermission plays in the same place, intermission screen. Weird, but you fail to notice a "Slipgate" (or teleport) sound at the beginning of the music track.
Links