Does your mouth size affect the sound and Volume of your singing,because my mouth is really small and I think that’s why my voice sounds really quiet and hollow?
Essentially yes 'resonance in the oral cavity' is a factor, however this is not the be all and end all. There are many different factors and this shouldn't limit you. Your diaphragm is where you should be singing from rather than your belly. Build that strength up with singing exercises. You will also want to be aware of keeping your voice open from the diaphragm and including your chest and mouth as much as possible. Practice singing open vowels from your diaphragm on scales and other excersises. Avoid foods like chocolate before singing. Don't let this concern discourage you or concern you. Work with what you've got!
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