Hoarseness is a general term which describes abnormal voice changes. While breathing, the vocal folds remain apart. When speaking or singing, they come together and as air leaves the lungs, they vibrate, producing sound. The more tightly the vocal folds are held and the smaller the vocal folds, the more rapidly they vibrate.
More rapid vibration makes a higher voice pitch.
Swelling or lumps on the vocal folds prevent them from coming together properly, which makes a change in the voice. There are many causes of hoarseness. Fortunately, most are not serious and tend to go away in a short period of time. The most common causes are acute laryngitis which usually occurs due to swelling from a common cold, upper respiratory tract viral infection, or irritation caused by excessive voice use such as screaming at a sporting event or rock concert. More prolonged hoarseness is usually due to using your voice either too much, too loudly, or improperly over extended periods of time.