MARK Snow is one of the most important contributors to the hit Fox series “The X-Files,” but he’s never appeared in an episode, never directed one and never written a single plot twist for the show’s famously bizarre stories.

Snow, a Brooklyn kid transplanted to the West Coast, is the music-driven series’ chief composer. While “The X-Files” promises that “The truth is out there” and explores the possibility of alien life on Earth, Snow is decidedly grounded in his own life.

He’s a Juilliard graduate who has written for “Pee-wee’s Playhouse” and won nine Emmys. He recently scored the upcoming Antonio Banderas film “Crazy in Alabama” and released a CD of his music, “The Snow Files.”

Post: What’s the role of music in television?

Snow: I think it should involve the audience in a plot to such a degree that viewers are unaware of how involved they actually are in the story line. At its best, music subliminally – and sometimes overtly – brings you so deeply in that you’re transported out of the reality of your living room. Unfortunately, music won’t save the day if it is a lousy TV show, but when all of the collaborative elements like the writing, the directing, the acting and the music are in sync – it’s magic.

Post: Hasn’t music always been used to enhance drama – in opera, for example, and early theater?

Snow: Sure. In the days of silent movies there was a pianist or organist playing live in the theater. If we listened to that now, it would sound kind of old-fashioned and cheap, but those were the pioneering days. In a funny way, what I do on “The X-Files” is a version of that. I have a very sophisticated electronic studio, and basically I do what those guys did: I play along with the picture. I improvise, and these improvisations become more and more defined and focused. But initially I look and I play along.

Post: It sounds as if you’re describing what the organist at Yankee Stadium does.

Snow: It is. That’s correct. If you listen to some film music without the film, it can be pretty terrible. The magic is in the marriage. That is the craft, that is the job.

Post: Your record “The Snow Files” does stand on its own, however. What makes it work?

Snow: It’s simple, really. For that album I chose material that is the most melodic and thematic. They are all songs without lyrics. “The X-Files” stuff is sort of ambient or atmospheric – it meanders and rambles a little bit, but the other tunes are very listenable.

Post: What’s the difference between what you do and what a pop songwriter does?

Snow: Great pop songs are usually very simple. There is power in that simplicity, power that reaches out and grabs you and makes you feel it. We as film composers aren’t always lucky enough to come up with compelling melodies. When we do, we have not only written a beautiful piece of music, but it also furthers the show.

Post: What is the hardest emotion to convey through music?

Snow: It’s not obvious. Take anger, jealously, sadness, happiness or remorse – those emotions are not that difficult to illustrate musically. What is difficult is neutral. If the director doesn’t have a focused picture of the scene, then you are trying to write for a non-point of view. Subtlety is the most difficult text to write for.

Post: Are there any guidelines like, strings are for love, drums connote danger, that kind of thing?

Snow: If one says, “Well, it’s a love story, so it has to be strings and piano” – that kind of thinking isn’t terribly creative. Once I spoke to Henry Mancini about this. He said when he wrote he would assign a character to a player and a sound. Like the tenor sax in the “Pink Panther” theme or the bass flutes in the “Elephant Walk.” What I am enjoying these days is the combination of all kinds of crazy ethnic sounds and world-music beat to underscore things that aren’t ethnic. Like in the movie “The Ice Storm.” The composer used Chinese gongs and percussion and a clarinet. I love that freedom to make those combinations. Sometimes when you don’t do the obvious is when it really works, and it also stands out.

Post: But surely there’s nothing wrong with using the obvious on occasion, like Chinese gongs in a Chinese temple scene.

Snow: It depends on what’s going on in the scene. Does the scene require the gong to set the place in the viewers mind, or does it need strings to set the mood of the characters emotionally?

Post: How often do you watch an episode of “The X-Files” before you start writing music.

Snow: I’ll watch a rough cut all the way through first, and that gets me thinking. When I get the final cut, I’ll start with a few small fragments of music that hopefully develop into the underscore. I get into an episode pretty quick.

Post: Are there disagreements about your musical choices?

Snow: I’ve been doing “The X-Files” going on seven years. They come over to the studio and listen to the music, and sometimes they’ll have a comment, like “We need a little more power here,” or “When the monster jumps out please hit the music a little harder.” But that’s basically it these days. But in other situations, where you are working with someone for the first time, I’m prepared for anything, including total rewrites. That’s part of the job, that’s also part of the fun. I love interpreting the abstract word musically.

Post: Have you had any “X-Files”-like experiences in your own life?

Snow: I had a home in Vermont that I sold last year. It had expansive views and it was very quiet. I was out alone one night I saw three light-type things that at first I thought were stars. But they kept coming at me in a group. They got closer and closer. It really gave me the willies. I’m looking at these things thinking, “This has got to be a joke.” To make a long story short, I know in my heart that this was something extraterrestrial. I am a believer.

Post: Do people believe you?

Snow: I don’t like to talk much about it, because people say, “Oh, bull—-, you work for ‘The X-Files,’” but it is what I saw and it is what I believe. There was no sound, there was no communicating, there was no probing, but I believe it was from outer space.

Post: Are we ready for the first contact, or would we just start shooting?

Snow: I think it’s a split. Half would shoot, half would invite the aliens over for a pastrami sandwich.