To the producers of "Noises Off," the change breathed new life into their comedy. The producers of "La Cage aux Folles" couldn't wait to tell everyone about theirs. Nor could those of "Torch Song Trilogy."

But the producers of "Hurlyburly" have been very quiet.

Changes in casts have been part of putting on a play for as long as there have been thespians. But in the age of People magazine -- not to mention the dullest Broadway season for new musicals and plays in memory -- cast changes are big news, often spelling success or failure for a production.

Take, for instance, "Noises Off" (Ethel Barrymore, 243 West 47th St.), a very funny play about the exploits of a tatty British acting troupe touring the provinces. A few weeks ago the cast was changed completely. The New York Times sent critic Frank Rich to re-review the play as though it were brand-new -- an exceptional practice in a town where there are enough new plays to keep half a dozen critics busy full time.

What Rich found could be expected. "With the exception of Carole Shelley," he wrote, "the new players are not as sharp as their predecessors, but . . . 'Noises Off' rips along most of the time."

A week later critic John Simon followed suit, writing in New York magazine that the new cast is "less amusing than the old . . . Yet with this cast or any other, including penguins or seals, 'Noises Off' is still the funniest farce on Broadway."

The producers were ecstatic. Advertising copy was recast to include new reviews. The marquee was changed. Sales of tickets, which had fallen to the point where they were offered at the half-price TKTS booth on 49th Street, climbed to new highs.

The same thing happened when Van Johnson surfaced in the lead in "La Cage aux Folles" (Palace, 47th Street and Broadway) and when Harvey Fierstein returned to "Torch Song Trilogy" (Helen Hayes, 240 West 44th St.). But when William Hurt, Sigourney Weaver, Christopher Walken, Harvey Keitel, Judith Ivey and Cynthia Nixon abandoned "Hurlyburly" en masse, no new reviews were written about the new cast.

Nothing against that new cast -- which is working with the same problems the original stars had with the script -- but one has to feel sorry for Mr. and Mrs. Out-of-towner, arriving to see William Hurt and Sigourney Weaver and ending up instead with Ron Silver and Christine Baranski.