Does size really matter in opera singers, wonders Justin Davidson? “There is a rough, unofficial consensus that in some operas size matters more than in others. Companies will bend over backward not to cast a fat Carmen or a slow-moving Zerlina in Mozart’s “Marriage of Figaro,” but all of Wagner, some Strauss and much Verdi are open to singers of any dimensions. As we whittle down the options for large singers, we also deplete the pool of people who can sing these demanding roles. Voices like Deborah Voigt’s are a precious resource.”