Before discussing stuttering, it is important to understand the concepts of speech fluency and disfluency. Fluency is generally described as the forward flow of speech. For most speakers, fluent speech appears easy and effortless. Fluent speech is generally free of interruptions, blockages, and repetitions or fragmentation of words. Disfluency is a breakdown in the forward flow of speech. For all speakers, a limited amount of disfluency is normal. For example, people may insert short sounds or words, such as “um”, “like”, or “uh”, when speaking. Also, speakers might repeat whole words or phrases (e.g., for clarification), or revise words or phrases. For the most part, the disfluencies appear effortless, and the speaker may appear to be unaware of any difficulty. For young children, disfluency is a part of the normal development of speech and language, especially during the preschool years (between the ages of 2-5). Virtually all children will go through a period of producing speech disfluencies when learning to speak. The disfluencies often appear as the child is learning mastery of the language and is faced with decisions concerning putting thoughts into words, selecting correct grammatical structures, and producing the sounds and words correctly. Typically, a child will have fewer than 10 disfluencies per 100 words, i. e., less than 10% of words will be produced disfluently.

Still, these disfluencies are not the same as stuttering. Stuttered speech is typically characterized by an excessive amount of disfluency (more than 10% of words), or by the speaker’s attempts to avoid disfluencies. The disfluencies produced by people who stutter are often similar to those of individuals who do not stutter, but certain types of disfluent behavior are more likely to appear in the speech of people who stutter. These disfluencies include sound and syllable repetitions (ca-ca-ca-cat), sound prolongations (sssss-salad, ffffff-fish), and complete blockages of respiratory airflow or sound production. These behaviors are referred to as stuttering-type disfluencies. An additional difference that is seen between normal disfluencies and stuttering-type disfluencies – the latter often appear much more effortful, and the timing/rhythm of the repetitions or words may become jerky and irregular.

Most people who stutter react negatively to their disfluencies. A person may develop a number of physical reactions including tension of the muscles involved in speech (e.g. tongue, jaw, lips, or chest) and tension in muscles not related to speech (e.g. shoulders, limbs, and forehead). In addition, people who stutter often develop negative emotional reactions to their stuttering, such as embarrassment, guilt, and frustration. Finally, many develop negative attitudes and beliefs about themselves and their speaking ability. These physiological, emotional, and attitudinal (cognitive) reactions are often very disruptive to the communication process–and to the person’s life in general.

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