The theme, "The X-Files", used more instrumental sections than most dramas. The theme song's famous whistle effect was inspired by the track "How Soon is Now" from The Smiths' 1985 album Meat Is Murder.
After attempting to craft the theme with different sound effects, Snow used a Proteus 2 rack-mount synth with an effect called "Whistling Joe".
After hearing this effect, Carter was "taken aback" and noted it is was "going to be good". According to the "Behind the Truth" segment on the first season DVD, Snow created the echo effect on the track by accident. He felt that after several revisions, something still was not right.
Carter walked out of the room and Snow put his hand and forearm on his keyboard in frustration. The keyboard had an echo effect setting that had accidentally been activated.
The resulting riff pleased Carter; Snow said, "this sound was in the keyboard. And that was it. "The second episode, "Deep Throat", marked Snow's debut as solo composer for an entire episode.
The production crew was determined to limit the music in the early episodes. The theme song appeared first in "Deep Throat".