The “Adam’s apple” is actually a little box which contains and protects the vocal cords, called the larynx. Girls’ are smaller than guys’, and don’t protrude as much. Thus the name Adam’s apple rather than Eve’s apple.
Most people don’t know that the primary purpose of the vocal cords is to block off the opening to the lungs when we swallow, so we don’t choke.
Put a finger on your Adam’s apple and swallow. You’ll feel the larynx rise to the top of your throat. The reason for this is that it serves as a kind of cork, stopping up the opening to the lungs (the esophagus). As this happens, the opening inside of the larynx also closes so nothing can get through. This little doorway inside of the larynx is opened and shut by the vocal cords, working like the inside folds of a set of curtains which pull the curtains shut.
So, the primary purpose of the vocal cords is not to make sounds, but to keep us alive by not letting food or liquid go into the lungs. Speaking and singing are secondary purposes.
This action by the larynx is vital to our existence, but is detrimental to our singing.
You see, as the larynx rises it reduces the area of the throat between the vocal cords and the head, When the throat becomes shorter the sound becomes smaller and more pinched. Quality is lost, high range is reduced and stress occurs.
The thing is, we can’t swallow and sing at the same time, so there is no reason for the larynx to be high while we are singing. Good singer’s must actually train it to stay low since it reflexively wants to rise when we sing.
There are excellent exercises available from private teachers or from recorded singing courses, but a good way to start your “larynx training program” i to be aware that this is probably happening, and to “think” it lower when you are singing. As you practice singing with the feeling of a low larynx it will learn and begin to stay low without your constant supervision.
This will make amazing differences in your vocal quality, range, singing dexterity and stamina.