These muscle movements are initiated, coordinated and controlled by the brain and monitored through the senses of hearing and touch. The air that is held in the lungs is gradually released, passing through the gently closed vocal folds thus causing vibration and producing the voice. The palate, tongue, jaw and lips move in precise ways to modify the sounds in order to make speech sounds. It is estimated that over three million Americans stutter. Stuttering affects individuals of all ages but occurs most frequently in young children between the ages of 2 and 6 who are developing language.
Boys are three times more likely to stutter than girls.
Most children, however, outgrow their stuttering, and it is estimated that less than 1 percent of adults stutter. Many individuals who stutter have become successful in careers that require public speaking. The list of individuals includes Winston Churchill, actress Marilyn Monroe, actors James Earl Jones, Bruce Willis and Jimmy Stewart, and singers Carly Simon and Mel Tillis, to name only a few. Scientists suspect a variety of causes. There is reason to believe that many forms of stuttering are genetically determined.