Born in New York City on April 19, 1914, Froos had wanted to be a singer since a young age. When she was four, she conducted a multi-song performance at the lodge owned by her father. Her mother forced her to leave, however, and was against her doing further performances. After three years of her repeatedly begging to be allowed to perform at her family's social parties with her mother only allowing her to do so rarely, she was noticed by a theatre booker at one of the social functions after singing accompaniment. Froos was able to convince her mother to, at the age of 7, allow her to act as a part of the Kiddie Cabaret group that performed vaudeville in Washington D.C.
