The picture demonstrates and names all of the components that make up the vocal tract. Those components interact together in the production of sound. Training the voice is the same as training on an instrument with one exception — you cannot see what you are doing! Instruments on which the student plays gives the teacher the ability to see what the learner is doing correctly or incorrectly and adjustments can be made accordingly. The voice is part of your body and the internal workings of the vocal tract cannot be seen. The singer hears from the inside, but the teachers hears it all. The mechanics of singing is coordinating all of the parts that work together to produce sound, and must work in harmony. When one part is out of sync, there is a domino effect impacting the others. Vocal problems develop over the course of time, but the trained ear (teacher) will hear those subtle changes and correct them before they become a problem.
The art of voice training is an intangible process. You cannot “see” the voice as its characteristics begin to shape. It is helpful and important to embed the picture of the vocal tract in your mind so that you can “see” the process from the inside. The teacher can then guide you as she/he directs you to perform certain physical functions that you can “feel” as the singing voice begins to take form.