I don't recall who said it, but someone said it in the DVD: Elvis, He touched me. If I understood it right what was said: Elvis had a very special voice that could reach up to 8 octaves. It doesn't mean he always sung them. Anyway if you listen to life concerts and studio tapes you hear him often sing in various voices. I mean one time you hear him sing Very high (even I can't reach that tone and I'm a girl, but then again I must admit I only can sing low voices.) and another time very low and in between.
Just watch the DVD: He touched me and let me know if I understood right. I really can recommend this dvd.
Be safe and take care,