BOOK REVIEW / FICTION : If Her Musical Talent Is to Develop, So Must She : DAUGHTERS OF SONG <i> by Paula Huston</i> ; Random House; $23, 363 pages

Courage is the theme of most coming-of-age stories, but the arena is usually war, hunting or sports--not, as in Paula Huston’s first novel, a classical conservatory in Baltimore where a 20-year-old piano student named Sylvia is wrestling with Beethoven’s last sonata, Opus 111.

Yet “Daughters of Song” is at least as exciting a read as any masculine version, despite a near-absence of blood and no bullets at all--largely because Huston has created in Sylvia as winning a heroine as American fiction has seen in years.

As a musical prodigy, Sylvia is a freak. As a young woman exploring life in the city after a sheltered upbringing in Minnesota, she is all too ordinary--and vulnerable.

Her octogenarian teacher, Cornelius Toft, an irascible former giant of the keyboard, terrifies her. Almost as frightening is the prospect of disappointing her loving but domineering father, who is paying the bills.

Sylvia is mugged by one of the vagrants who lives in the alleys around the conservatory. She has to adapt to exotic roommates--Marushka, a free-spirited Ukrainian; Colette, a moody African American from New Orleans. She is bewildered by young men--Peter, her platonic friend, whose tastes run to jazz; Jan, who loves her; David, who goes to bed with her.

Sylvia knows, vaguely, that she has to grow up. So far, her talent has protected her from life, but to allow that talent to develop, she has to let life in, even if it causes her pain.

The question is how. Toft and his most famous pupil, Moon Ja Koh, are iron-willed people who have pushed love aside to concentrate on their art. Katerina Haupt, another piano teacher, has remained open to love but fears that her art has suffered. Conflicting advice comes from Sylvia’s roommates, from Peter, from Jan--even from Beethoven, whose music, more than anything else, is a testament to courage.

Sylvia’s greatest asset in music--and, seemingly, her greatest liability in life--is her thin skin.

“She has felt haunted, as though there is a little girl, 7 or 8 years old perhaps, who lives inside her and is having to run as fast as she can just to keep up . . . tears of fright streaming down her face. . . .

“She is so often out of control, so often dominated by her emotions, that on occasion . . . she has worried about her own sanity. How many times has she cried simply because something was beautiful? Normal people don’t behave this way.”

But normal people also can’t create beauty the way Sylvia can when her complexities are meshing just right. “So,” Haupt thinks during a recital at which Sylvia’s playing has veered from the mediocre to the sublime. “She has that problem, does she? One of those flighty, inconsistent, incredibly gifted types--no wonder Cornelius gets so wound up about her.”

“Daughters of Song” is much like that recital--a mixed performance, with the good stuff predominating.

Huston’s prose is rich, sensuous, alive. In a hard-boiled age, she dares to write openly about the emotions. She persuasively renders the hothouse atmosphere of the conservatory, its friendships and rivalries.

As Sylvia learns not to depend too much on anybody’s advice, Huston shows what awaits her: Koh’s self-sufficiency and glamorous image cracking under the pressures of mid-career; Haupt trying to sum things up as she nears the end of hers.

Lest we wonder what all this high culture has to do with the messy, unclassical world outside, Huston gives us a subplot about two homeless men, Tee and Bellyman, whose lives briefly intersect Sylvia’s.

As art, this fails.

The men are sentimental projections rather than people. As an act of bravery, though, it helps explain how Huston has made the heart of the story--the coming-of-age part--so convincing.