Explanation

The vowel [i] has three special features. First, lips are spread wide (not rounded). Second, the tongue is high and forward in the mouth. Third, air does not go through the nose.

When you say [i] as in “bee,” your lips pull to the sides. Your tongue rises toward the front of your mouth roof. This creates the high front vowel.

Each vowel has its own combination of features. Position of tongue and lips determines which vowel you make.