I think the tip is referring more about the cadence or the character of how you speak, rather than the tonal range. I agree it's always of benefit to stretch your range and I would love to push my range further. I'll try some of your tips. I just speak in a lazy monotone, and trying to sing like Elliott Smith wasn't working for me, no matter how hard I wished it would. After two albums I really tried to figure out exactly what "my voice" is, now I feel a lot more of my own personality comes through in my music, instead of some kind of awful butchery of someone else's style.