Marshmallows and singing, what do they have in common. It is a tool that I have been using with my voice students and it has helped open the sound up by eliminating the ability to close on consanents. Side benefits are laughter and relaxed jaw and tongue! I purchased a book called "Gadgets for great singing" by Christy Elsner. She describes how to use it by 1. Insert a large sized marshmallow into the mouth with the flat side on the tongue. 2. Sing the phrase or the entire song without letting the roof of the mouth touch the top of the marshmallow. With my students this has really helped them relax the throat and open up their sound, especially with high notes. Their intonation has improved greatly as well, I think this happens mainly because they can hear it much better! Afterwards they get to eat the marshmallow, although I have them hold it until the end of the lesson 😉🎶.
Genius trick for singing easily