Is your whispering due to pain from the breathing tube or something else? I had throat pain from the breathing tube for the first day or two, but I could talk just fine. It wouldn't hurt to give the a quick call, or have someone call for you, to let them know how you're feeling.
I did not have a sore throat with this surgery but I have with some others. I was told by the nurse the tube the put down your throat can cause irritation and you may have a hard time talking afterwards. But I am not sure how long that is to last. You may want to call your dr if it does not get better for you. (((HUGS)))