Here's a short one-minute clip where he says, "Critics says I can't sing. I croak. Why don't critics say that same thing about Tom Waits? Critics say my voice is shot. That I have no voice. Why don't they say those things about Leonard Cohen? Why do I get special treatment?"

http://deredactie.be/cm/vrtnieuws/video ... /1.2232045
It's clear it's all said with humor though.
By the way, if anyone has not heard Dylan's new album of standards, Shadows in the Night, do yourself a favor and pick it up. Speaking of his voice, Dylan hasn't sounded as good as he sounds on this record in many, many years.