Vocal warm up part 1 How to hummmm to warm up your singing voice Humming is a very wonderful way to warm up your voice but when you strain to do it, you get unwanted tension as the submental space becomes tight, closing the vocal tracts, increasing the height of the larynx and tightening the vocal cords. This also constricts proper airflow, making flow phonation hard. So place your thumb under your submental space to ensure it's not popping out and tight and enjoy a wonderful hum for your vocal