This is really interesting. My muscles get tight in my throat when I start to read to my grandson or husband....sometimes when I sing, but not as much. I am sure it's related to not having enough O2 prior to the new heart valve. One thing I've noticed which helps is a throat "chi" massage as done on a gi gong/yoga tape I have. Rubbing the hands together to build up the chi, then running them down the throat, one after the other. If nothing else it brings warmth to the area and, for me at least, a relaxation which helps.