When Meredith Monk sings, the whole world understands. Her radical style taps many cultures

Meredith Monk is an uncommon artist. Though her main interest is music, her talent ranges over many fields, from stage directing to filmmaking. She brings her own unique sound style to each of them.

Her latest theater piece, ''Specimen Days,'' was presented by the New York Shakespeare Festival in a production that will run again Feb. 16-28. And you can hear her latest compositions on a splendid new record, Dolmen Music (ECM-1-1197) , which recently won a West German prize as best recording of the year. Or you can hear the works on that disc - and more - performed live during her major tour of the West Coast and Europe, that is just getting started. It's a busy time for Miss Monk and her colleagues, which is good news for listeners who enjoy opening their ears to new and adventurous music.

Listening to Miss Monk's music is always an ear-opening experience. Her solo works, such as those on Side 1 of ''Dolmen Music,'' are virtuoso exercises in mood and texture, calling on all kinds of vocal resources not usually found in Western composition, from glottal stops to wailing ululations. Her ensemble pieces extend her personal techniques to other voices, while allowing them room for their own expressions. The dominant effect is one of eerie loveliness.

Over lunch recently, Miss Monk sounded like a composer even when discussing her activity as filmmaker or stage director. She said, for example, that her most recent theater work has been quite abstract. ''It's not laden with content, '' she explained. ''It's musical.''

The key word for her seems to be ''musical.'' Even her stage work, she feels, has a musical structure. ''You'd know right away it was a musician who did this, '' she says. ''Even the images are musical. When I use images, I'm like an orchestrator.''

Just as her theater work is musical, her musical compositions are inherently theatrical, even when they are sung and played ''straight'' on a bare stage. This is partly because of the exotic voice-sounds Miss Monk uses instead of words for her songs. ''I rarely use texts because voice itself is such a strong, rich language,'' she explains. ''You hardly need another language on top of it. The syllables I use are extensions of the music. I don't think English is any more interesting.''

And there's another reason, recalling the old ideal of music as a universal language. ''I can do my music all over the world,'' she says, ''and people can respond directly, without having to go through language. . . . I'm trying to approach a vocal music that's both primordial and futuristic, and this is my way.'' Futuristic? ''Sure. Maybe there won't be language differentiation in the future.''

Miss Monk started on her adventurous pathways early. ''I've always been singing,'' she recalls. ''My mother and grandfather and great-grandfather were all singers. I began writing vocal music when I was a child. I was writing piano compositions by the time I was a teen-ager.''

But following the family tradition wasn't enough. ''I wanted to do something else,'' she says. ''I wanted my own territory. This led me to dance, which will always be a part of my life.''

It was her early dance experience that suggested the direction her music would take. ''In modern dance,'' she explains, ''it's taken for granted that a person develops her own style and vocabulary of movement. But I realized this had never been done, vocally. I wanted to create a very personal vocal style, to stretch the voice in as many ways as I could. I was interested in using the voice as an instrument, as a source of energy and impulse, to get different registers and kinds of texture.''

This impulse came to her ''in a flash'' as she practiced the piano one day. ''I suddenly felt the voice could be as flexible as the spine,'' she recalls. ''I realized the voice could move in as many ways as a body can. From that time on, I started working on my vocal music. I have a wide range, so I could work with my own instrument.''

From the beginning, her methods were radical. ''A lot of it was learning how to sing a melody in a way that was separate from Western training,'' she says. ''It involved stripping away. Not stripping away technique - this singing requires a lot of technique and strength - but stripping away the idea that you can only sing something in a certain manner. The whole Western tradition is based on certain tones and sounds. I had to throw a lot of that out, using a trial-and-error method on my own voice. I just tried things - I was already an artist, so I knew what I was doing - and after a few years I started going to other sources, too. For example, I began to realize that some cultures have a glottal break or ululation sound, and that I found this interesting. But it all stemmed from my personal experiments.''Her approach to dance was similar. ''I wanted to throw away all the trained responses and start from scratch,'' she recalls, ''with a natural and organic style that was very much my own. I wanted to get to a very straightforward and truthful expression, and I knew I couldn't get this by training and being in class.'' Later, she applied the same ideas to work in theater and film.Like many of today's leading young composers, Miss Monk went through a ''minimalist'' phase early in her career. In her album ''Key,'' for example, ''each song has one vocal quality.'' But there's more to it than that. ''I was also dealing with range a lot,'' she says, ''and I was very aware of how the voice is directly hooked up to the emotional palette. You can get to emotions you can hardly reach with any other medium, certainly not verbally. And I felt I was connecting with ancient traditions and roots, as well as futuristic ones.''At the same time, like many of her contemporaries, Miss Monk is uncomfortable with the ''minimalist'' label. ''I was always more of a maximalist , really. It wasn't very interesting to pare everything down to one element. But I was working in fairly simple ways. I wanted to get back to real basics.''Though so-called ''minimalists'' generally squirm under that heading, it has been useful in describing a great deal of recent musical activity by composers as different as Meredith Monk and Philip Glass, Steve Reich and Jon Gibson.Why should that be? The answer says a lot about current musical impulses and ideas. ''The Western classical tradition of the '40s, '50s, and '60s got detached from any basic consciousness,'' Miss Monk says. ''When I hear that music - and I try not to hear it - it's all head, as if nothing existed beneath the chin. A lot of people started to feel there was nowhere to go in that direction - that a more human, more essential, more vital expression was needed.''Also, I have the feeling that rock-and-roll had a lot to do with it. I used to play in a rock band, and I still think about how strong it can be - how the beat is involved with heartbeat, pulse, feeling. I listened to jazz around the middle '60s, too. It's all connected.''So unusual and eclectic is the Monk approach that she encounters problems peculiar to her own work. For instance, it isn't easy to come up with a standard-style score for much of her music. ''Phrases are scored, and I usually know the overall form,'' she says. ''But in rehearsal, I work on the phrases right with the voices, as if they were bodies. It's very alive, like something from the oral tradition. In a work like 'Tablet, ' there are sections you can't write out at all, so you just put 'improvisation.' Also in 'Dolmen Music,' there are parts that would take 15 years to notate completely.''And there are places where the singers have room to play around within the set form, and these sections are different each time they're performed. . . . So if someone wanted to learn the piece, they'd need a score and a tape recording. After all, how can you write out a timbre or a texture?'' By the same token, a director restaging a ''Specimen Days'' would need a videotape as well as a script, to get a complete idea of what the creator intended.For the immediate future, Miss Monk expects to immerse herself more completely in music, and perhaps in film, leaving aside the demanding and time-consuming process of conceiving and directing new theater pieces. She will never leave theater behind, but music is calling her very insistently these days , and will probably claim most of her attention for the next few years.Most important of all, she says, is communicating with her audience in as pure and direct a way as possible. Sometimes she feels the temptation to popularize her music, incorporating it in a rock framework - or some such package - and getting rich from it. But she rejects that approach, just as she rejects the ''anticommunication'' she sees in ''arty, deliberately difficult'' work that ''masquerades as avant-gardism.'' She isn't in that mold at all, she asserts, despite the challenging nature of her art. ''I want to reach people's hearts,'' she says. ''I want my music to be a heart thing, not just a mind thing. . . .''