We use our face muscles all the time to speak clearly. Your “vocal apparatus” is your lips, tongue, teeth, top of the mouth and the voice box in your throat. There are muscles in the lips, tongue and throat as well as your cheeks and jaw. It takes about 100 muscles to speak! To speak well, it's important to move, tense or relax the muscles in your face at the right time. It may seem strange to think about muscles in your face but, really, speaking is like playing an instrument or sport. The muscles need to learn and remember how to make the correct action. This is called "muscle memory”.
Think of sports; when you kick the ball, your body learns where to place your foot and which muscles to snap into action. You keep practicing that kick, maybe fifty times. Then one day your body remembers and you know the ball will go where you aim it.
It's the same with language. It's a muscular skill that creates sound. The sound is made by your face and throat muscles and it is important to know which muscles you need to use. Your cheek muscles and jaw muscles help create the “tense” sounds. Your throat muscles create the vibration for “voiced” sounds, such as “gg” and “mm” and your tongue muscle is needed for most language sounds. And just as in sport or music, creating muscle memory means practicing!
The important thing when practicing is to be careful to use the correct form. A good place to start is to identify and become comfortable thinking about the parts of your mouth. It's difficult for some people to think about their lips and tongue because it's so intimate, but these are indispensable tools for communication. At first, try tensing and relaxing your lips and cheeks, moving them to see how wide or tight they can go. Then focus on your tongue and slowly touch all the parts of your interior mouth: the oral cavity. What is up? What is down? Feel for the front teeth and the back of the throat. The mouth feels like a big cave inside the teeth. Feel the area behind the upper teeth, down where the tongue can relax and how far back your tongue can go (without choking!) Try it with your eyes closed. Another time it might be useful to look in a mirror and watch your face while you make certain sounds. Don't worry, many people are uncomfortable watching themselves speak, but try it- it might be fun!
At first, practice as slowly and perfectly as possible.
Of course, you can't worry about perfection when you're in the middle of a conversation but you do need to practice perfection beforehand, so that when you want to make the right sound, your mouth knows how to do it and can do it quickly and correctly. Once you are sure of the individual sound, see how many times you can do it perfectly. At first, three or four times will be a challenge. Keep going, and soon your new language will be flowing out of you, smoothly and clearly!