There is a major difference in this production, however. Seattle Opera often uses a double cast, and in this, one Rosina is a soprano and one a mezzo soprano. Coburn and Lindsey have different vocal timbres, but what matters, Williamson says, is who they are as musicians as reflected in their personalities. “They are both such strong characters on stage, they make you laugh, cry, feel.”

One aria is pitched a semitone apart for their voices. Where Coburn sings it in F major, Lindsey sings it in E Major, the key used in Rossini’s original production. Not a problem except when you are singing with someone else, and Rosina spends considerable time singing in thirds with the maid Berta, veteran Seattle Opera artist soprano Sally Wolf.

“It was one of our big issues, how do we do that,” says Williamson. “We ended up with two versions of the role. When Sally sings with Sarah, she sings the lower voice, when she sings with Kate, she sings the higher one. Sally’s fantastic. She owns the stage when she’s up. When I asked if she’d do it, I wasn’t surprised when she said Okay.”

I read this here, at The Gathering Note.

Very seldom have we had to do something in different keys due to our double casts. I can’t even remember the last time this happened, in fact. We do sometimes have to do things differently for the singers, of course — tempi can be different, as can spots where we slow down or speed up. No matter what the biggest issue is remember who’s on for the performance!