Khan's doctor has ordered the iconic singer to go on an extended vocal rest, forcing the cancelation of appearances at The Capital Jazz Festival at the Merriweather Post Pavilion in Columbia, MD (Saturday, June 8); the Pittsburgh International Jazz Festival, held outdoors in the downtown Cultural District in Pittsburg, PA (June 9); an appearance with the Columbus Symphony Orchestra at Columbus Commons in Columbus, OH (June 14) and Joni: A Portrait in Song at Massey Hall in Toronto, Canada (June 18 and 19).

Khan still plans to attend the Apollo Spring Gala on Monday, June 10, at the Apollo Theater in Harlem, New York where she will be inducted into the Apollo Legends Hall of Fame.

The Apollo ha tapped Erykah Badu to induct Khan and the event will include special tribute performances by Patti LaBelle , Mary J. Blige and Deborah Cox .

Khan has also pushed back the release of her new album, "The iKhan Project: Alive," from the original July 2nd release date until this fall. Her manager Tammy McCrary explains, "Due to her doctor's orders, it's best that we move the date to give her the proper and adequate time to promote and market the new album."