Known as "Mama Jan," Jan Smith is one of the most famous vocal coaches around. Whose voice was she famously hired to guide through puberty?

Jan Smith helped Usher in the early 1990s and was brought on to help Bieber when his voice started struggling. In an article in The Guardian, Bieber was quoted as saying: "She has me doing vocal ... exercises regularly."

Asked by Tom Cohen · Last updated 5 years ago · 297 views