I've always been told that it tightens up your chords. I guess your chords are like chewed gum. If you drink ice cold water while you chewing gum, it gets all tough and hard to chew. So, I'm assuming that is similar. Why would you add something cold to something that is supposed to be warmed up? That is just what i've always thought. I'm going to ask my voice teacher and get back to ya with the correct answer, if mine isn't. Many blessings...