This might seem like a trivial matter, but tonight I listened to the Tony performance of "Omar Sharif" from The Band's Visit, and noticed that there was minimal vibrato in Katrina Lenk's performance. Is this common, or are there many other instances of such a vibrato-free vocal performance?
I think this is a case of a combination of an actor who tends to sing with quite a bit of straight-tone making a further conscious decision about the sound of her character's voice. Chilina Kennedy, who did the national tour, sings with quite a bit more vibrato (but less than I've heard her in most other roles):
But Katrina Lenk really does sing with unusually limited vibrato across her performances (listening to her "Someone Is Waiting" and there are some long notes higher in her range that she sings totally straight-toned). Vibrato, for singers who can really control it, is part of the storytelling toolkit, and I do think you've helped me pinpoint why her voice sometimes strikes me as cool or unemotional (worked great for Dina where she found lots of other colors within that sound, maybe not for every part).
