Let’s see, what the author, S.Chandler says about it?
“When referring to people whose speaking voices are pleasing to listen
to, many people use words like “melodious” and “well-modulated.” This
is a good hint to tell if someone is complimenting a great speaking voice.
You are not stuck with the voice you have now. Start singing, and soon
you’ll be creating the voice you’d like to have. The stronger your voice,
the stronger your confidence and the stronger your confidence, the
easier it is to motivate yourself.“
Honestly, I don’t know how the strenght of the voice could have some impact to the self motivation if the person doesn’t work with his/her voice. On the other hand, yes, if the voice is like a mice’s, very weak and without any authority, it’s hard. I should start singing more. But I’ve lost my voice when I started to drink and shout in the parties 🙂