I have a few friends who have hearing problems and I was wondering if deaf people can whistle? None of my friends can. I never thought that this was unusual until we read an article on the web that was wondering the same.

WHAT A GREAT QUESTION! The answer will largely depend on how deaf the person is and when the problem started. People who are profoundly deaf from birth will probably not be able to whistle, since (like speech) it will require some auditory feedback, which they lack. Conversely, people who are not completely deaf and/or developed it in adulthood (after they learned to whistle) should have very little problem.