Anatomy of the Voice System
One of the simplest ways to think about how the voice works is to consider “power,” “source” and “filter.” The power for the voice is the air from the lungs. The vocal folds vibrate in response to this and create sound waves. Therefore, the larynx and vocal folds are the source of the voice. In order to have a unique sound and also to perceive different speech sounds and words, the sound waves need to bounce around inside of the spaces of our throat and head. This bouncing around shapes the sound by changing or filtering parts of the sound waves.
The larynx, a cartilage structure in the neck, is often called the “voice box.” The vocal folds are inside of it. The larynx works like a valve for different functions. It is closed during swallowing (to prevent food from entering the airway), open when breathing and semi-closed (vocal folds only) when speaking or singing.
“Pharynx” is the physiologic name for the throat. There are actually three parts to the pharynx: the nasopharynx (high up behind the nose), oropharynx (the part you can see when you say “ah”) and hypopharynx (the area surrounding the larynx).
The vocal folds each have a muscle inside of them called the thyroarytenoid muscle. The muscle has a cover of multiple layers for cushioning and vibration. The inner two layers are somewhat stiff and are called the vocal ligament. The outer layer is jelly-like and fluid. This is called the superficial lamina propria. The entire vocal fold is then covered with a thin layer of epithelium (skin). The skin is kept moist with a small amount of thin mucus in order to prevent friction from irritating the vocal folds as they vibrate against one another.
Source: Barbara M. Wilson Arboleda, M.S., CCC-SLP