CHICAGO -- In a family of vocalists, it was Cleotha Staples' smooth and velvety voice that helped set apart the sound of the influential gospel group the Staple Singers.Ms. Staples, the eldest sister and member of the group her father, Roebuck "Pops" Staples, started in the 1940s, died Thursday at age 78.Ms. Staples, known as "Cleedi," was inducted into the Rock and Roll Hall of Fame with her family in 1999. The Staple Singers gained a huge audience with their first No. 1 hit I'll Take You There in 1972 and followed with Top 40 hits Respect Yourself, Heavy Makes You Happy and If You're Ready (Come Go With Me).