Stuttering

Stuttering, also known as stammering, is a speech disorder characterized externally by involuntary repetitions and prolongations of sounds, syllables, words, or phrases as well as involuntary silent pauses or blocks in which the person who stutters is unable to produce sounds.^[2][3]

The term stuttering as defined by listeners is most commonly associated with involuntary sound repetition, but it also encompasses the abnormal hesitation or pausing before speech, referred to by people who stutter as blocks, and the prolongation of certain sounds, usually vowels or semivowels. According to adults who stutter, stuttering is defined as a "constellation of experiences" expanding beyond the external disfluencies that are apparent to the listener. In fact, most of the experience of stuttering is internal and encompasses more experiences beyond the external speech disfluencies that are not observable by the listener. The moment of stuttering often begins before the disfluency is produced, described as a moment of anticipation - where the person who stutters knows which word they are going to stutter on.^[4] The sensation of losing control and anticipation of a stutter can lead people who stutter to react in different ways including behavioral and cognitive reactions. Some behavioral reactions can manifest outwardly and be observed as physical tension or struggle anywhere in the body.^[4] Almost 80 million people worldwide stutter, about 1% of the world's population.^[5]

Stuttering is not connected to the physical production of speech sounds or putting thoughts into words. Acute nervousness and stress are not thought to cause stuttering, but they can trigger stuttering in people who have the speech disorder, and living with a stigmatized disability can result in anxiety and high allostatic stress load (chronic nervousness and stress). Neither acute nor chronic stress, however, itself creates any predisposition to stuttering.

The disorder is variable, which means that in certain situations, such as talking on the telephone or in a large group, the stuttering might be more or less noticeable. People who stutter often find that their stuttering fluctuates, sometimes at random.^[6]