Stress can cause anxiety in anyone. Whether the anxiety is minimal or severe depends on each individual person. Under stress, it is normal and acceptable for people's voices to waver. Speakers under stress may contract the muscles used to produce speech, increasing vocal pitch. This would generally not happen in a stress-free situation. Typically, when under stress, people speak more quickly. This sometimes causes them to stumble over words or get stuck on a syllable. In most cases they tend to repeat words or phrases as they struggle to speak, present, etc. under stress. Another common "symptom" under stress is the addition of interjections, such as "like", "uhm" and "uh" during speech. These are considered normal and acceptable dysfluencies. The simple task of saying colors in front of an audience was used as a study. They found that under stress, pressure, anxiety and whatever else you feel while speaking in public, non-stutterers went from zero percent disfluency to four percent. On the other hand, those who stuttered normally had a disfluency of between 1% and 9%. (Perkins) An interesting fact is that stutterers are able to speak normally with infants, children and animals. This audience is non-threatening and the speaker is comfortable. It is also common for stutterers to speak aloud to themselves without or with very little