Liv Ullman in "Mama"

Liv Ullman, famous for her roles in Ingmar Bergman films, was chosen to star in the Rodgers and Hammerstein musical “I Remember Mama,” although her voice left a lot to be desired. In her autobiography, she writes:

“Could you please sing a little tune?,” Richard Rodgers asks politely. “It will make it so much easier for me when I compose your songs.”

“I don’t dare to.”

“Sooner or later you will have to sing anyway,” the old genius says mildly. “This is a musical.”

“Oh, please wait—I am so ashamed of my voice.”

“I have heard it all. Nothing would surprise me,” he comforts me. “Don’t be afraid. I just need to know your key. Sing anything. Sing ‘Happy Birthday to

You.’ The lovely man takes my hand and looks at me encouragingly.”

I sing.

Before my eyes he ages 20 years.

From wikipedia:

"Critics found Mama to be old-fashioned and corny, and all were quick to describe the musically disinclined Ullmann as miscast...."