Where is my larynx and what is it doing all day?
People have two big tubes in their necks, the esophagus, which brings food into the body and the trachea, or windpipe, which handles air. Your windpipe is what is pushing out the front of your neck. The esophagus is behind it. At the top of the windpipe is the larynx. If you can find your Adam's apple put your finger on it, you are touching your larynx.
The larynx, specifically its epiglottis, closes off access to the windpipe when food is passing over it on the way to the esophagus. This usually prevents you from choking and always prevents you from swallowing and talking at the same time. The larynx also houses your vocal cords. If the vocal cords are tensed when air is passing through them they vibrate and frequencies are added, volumes and pitches are modulated, and the air is vested with a more complicated timbre. In phonetics this phenomenon is called voicing. So, your larynx is a multifunctional organ involved in safe breathing and speaking.
The story of the baby’s descending larynx
An infant's larynx is not like your larynx. It is more like the larynx found in most other mammals. A mature human larynx is positioned in a lower part of the throat than the larynx of babies and most mammals. Imagine gazelles drinking from a water hole. You could imagine them drinking all day and never have to imagine them lifting their mouths from the water. Gazelles can drink and breathe at the same time. So can bears. You can’t. Babies can.
"Evolution" lowered the human larynx which increased the size of the pharynx and improved the strength and variety of sounds humans make. This larynx position forces humans to take breaths at drinking fountains. It also increases our chances of choking while eating. In exchange for these disadvantages we can talk to each other and listen to the rich voice of Barry White. And while the tones of White’s freakishly low larynx and the bass heavy cranial resonance it affords lulls infants to sleep, a baby eventually wakes up wanting not music or conversation, but milk. Lots and lots of warm milk. And since evolution knew a lower larynx would be an unacceptable choking risk for breast feeding infants, It made sure the larynx began high and descended as the baby matured.
The larynx of youth, the larynx near death.
When a boy becomes a man his sweet angel voice may be replaced with wild intonational spikes and random nervous honking. His larynx is growing. The cartilage at the front of the larynx will eventually tilt and be pushed forward to display a proud Adam's apple. The vocal cords are getting longer and thicker resulting in a deeper voice. A young woman's larynx changes as well, but it's not so noticeable.
Eventually we get old and our bodies begin to malfunction. Most disorders of the larynx occur after 55. The vocal cords of men atrophy and the pitch of their voices can rise around 35 hz*. While the hormonal changes women suffer during menopause wreak havoc on their body they also cause a thickening of the vocal cords and cause edema which lowers her voice 10-15 hz. Cancer of the larynx, a disease suffered mostly by smokers, can also alter your voice as the tumours normally grow on the vocal cords. This voice change might also be accompanied by louder breathing. Normally when you breathe your vocal cords are relaxed so no sound is produced but a tumor can cause interference with your airflow. These noticable changes in voice allow many people to detect cancer of the larynx early when the cure rate is a nice plump 80%**.