I got to see her in 1978, a month before I left the Bay Area for Seattle and a year before she died of breast cancer. She opened for Al Green. A great double bill if there ever was one.

Here is a link to a bio of her where it states she had a five octave voice.

http://en.wikipedia.org/wiki/Minnie_Riperton

or for a sample

http://www.minnieriperton.com/sub/lyrics.html