What's this -- a composer who wants all to understand his music?

Pulitzer Prize-winning composer Michael Colgrass is trying to tear down the enigmatic image of contemporary classical music.

Colgrass, articulate and approachable, doesn't agree with composers who assume their music will never be understood by general audiences. And he makes no attempt to shroud his own work in mystery.

''When I first conceive of a piece of music,'' he says, ''I don't write anything down. I just walk around in the apartment making funny noises. And then when I get it the way I like it, I write it down.''

A lone wolf in the music field since graduating from the University of Illinois in 1956, he spent 10 years in New York City working as a free-lance percussionist rather than signing with a particular group. To have done otherwise, he says, would have taken him away from composing.

Colgrass has composed works for the New York Philharmonic, the Detroit Symphony, and other major orchestras, and he has had works recorded under a variety of labels. The Boston Symphony Orchestra under Erich Leinsdorf, for instance, recorded his 1966 ''As Quiet As'' for RCA Victor. His 1978 Pulitzer Prize for Music was for ''Deja Vu,'' a work for percussion quartet and orchestra written for the New York Philharmonic.

I spoke with him when he was here recently in connection with a five-part series to air this fall on PBS called ''Soundings,'' produced by Boston's WGBH. One of the programs features Colgrass. ''Soundings'' will try to help people appreciate contemporary classical music by presenting a personal portrait of individual composers, then playing some of their music. Viewers of the program on Colgrass will get a sampling of his distinctive music, some of which includes helpings of dance, drama, and poetry. They will also see him conducting one of his workshops on music, complete with a blackboard exercise where students take a stab at composing by forming shapes that suggest sounds.

That Colgrass should be on a program explaining music is appropriate. He feels strongly that contemporary composers can do more to help the public understand their music. ''I put the responsibility on myself to communicate. If you try hard enough you can find a way to communicate.''

Colgrass, who lives in Toronto but is an American citizen, uses his workshops and his appearances with orchestras -- as well as his random encounters with people boggled by contemporary classical music -- to do exactly that. In one of his bimonthly columns for Music Magazine (his wife, Ulla, is the editor and founder), Colgrass wrote: ''I believe the general public is capable of understanding a good deal more than we give it credit for, and that with our snobbish attitude about classical music we've been talking down to the public for too long. The time has come to shake classical music free from its past . . . and direct it toward people living today.''

Colgrass would go so far as to suggest that orchestra conductors invite living composers to chat with audiences before a performance of their music - and explain exactly what they were trying to do when they wrote down all those notes.

He also feels contemporary classical music is often ''lost in a large concert hall'' and he'd be more comfortable seeing his audiences seated on cushions in a smaller, less formal setting.

Putting Colgrass's explaining skills to the test, I asked him what contemporary classical music should do for the listener.

''I won't say what it should do for them. Because music, like any experience, is personal. You'll enjoy it your way, I enjoy it mine. But I think that what's going to happen with viewers, especially Americans, is that they're going to make pictures while they're watching.

''When I'm writing I'm really thinking about the performer. He is the person who has to render it, reproduce it. In the first place, it has to be possible.

''I'm very considerate about the musicians, because I've been one myself. I know what it's like to get a part written for you that's either impossible to play or does not sound in character with your instrument.''

But behind these mechanics, what is a composer trying to do?

''I think a composer feels something, and he would like to impart that feeling. But once he's put it down, do you get the same feeling he had? Maybe he put down something that's red. And you got orange from it. At least you got something from it. Some color.''

Colgrass would define music as ''the mathematical measurement of emotion.'' He adds, ''If you've ever looked at a score of Mozart, at its highest, most emotional moment, what makes that moment the way it is is a highly dissected measurement of time and tonality.''

Asked to contrast classical music and popular, Colgrass remarked that ''one of the differences is that classical music develops an idea. If you have a rock tune, you present the tune, and you keep presenting the tune. And then it finishes. If you have a little digression, you come back and it finishes.''

''A jazz tune, too,'' he says. ''You have the riff, as it used to be called, and then you have a number of choruses, and then you finish off with the riff again.

''But in classical music, what you do is you present a theme, or maybe two themes, and you develop those themes. You dissect them and you go over and over and over it 15 different ways. Maybe 25. Until you have more or less seen every perspective of it. Some people aren't so patient with that.''