This year's winner of the John Simmons Award for short fiction tracks a small group--musicians, mainly, one an artist--who come to maturity in the late '60s and try to hold life on an even keel in the decades after. The first of the dozen here may be the best, at least in pure artistry, as a flute soloist performs a work (""Bach Suite"") and at the same time thinks about his childhood fear of drowning. In general, Wyatt's details stay far the more fascinating when he sticks close to music, as in ""Half a Flute,"" about an old European instrument-maker and a young flutist--by name James Wallace, the book's main character--who joins the Marine Corps band to avoid Vietnam but ends up being lonely, doing drugs, and breaking down. Carrying on into life, the stories can grow quickly more commonplace and familiar, as friendships, courtships, matings, marriages--and the many failures of same--make their ways forward, much too often seeming more important to the teller than to the reader. The innate interest in details of teaching kids how to play flute, for example (""Teaching""), far outreaches that in the wrenched and postured meanings of the teacher's fling with a student's arty mother. An epistolary story like ""Letters from J,"" admittedly a verbal tour de force, is nevertheless jejune in content and self-conscious; and some will be hard pressed to forgive the recurring saccharine--as in ""Ghosts,"" where a newborn is ""as fresh as the newly washed sunlight."" Still, Wyatt can also observe more durable moments of subtle beauty; movingly portray a father-tyrannized childhood (""Indonesia""); and keep a long death-by-cancer story from foundering, partly by making the details of wooden flute-making a vital part of it (""Raag Yaman""). Stories, in all, then, that play the range of excellence from high to low: not always captivating, sometimes quite lovely.