Watch the video on this page: https://essentialsoflinguistics.pressbooks.com/chapter/2-2-how-humans-produce-speech/
So, we produce sound using the ENERGY from the air released by our lungs, which is then VIBRATED as is passes through the vocal folds/glottis. That vibration is RESONATED in any of the head, nasal, mouth and chest cavities and finally ARTICULATED by the lips, teeth and tongue.
This process is what gives you PROJECTION and ARTICULATION, or, in other words, allows you to be heard and understood.
This basic sound can then be manipulated in a variety of ways to communicate character, story and emotion. You can change the following: