<unk> , also known as stammering, is a speech disorder in which the flow of speech is disrupted 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. The term<unk>  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 Watkins et al.,<unk>  is a disorder of "selection, initiation, and execution of motor sequences necessary for fluent speech production". For many people who stutter, repetition is the main concern. The term<unk> " covers a wide range of severity, from barely perceptible impediments that are largely cosmetic to severe symptoms that effectively prevent oral communication. Almost 70 million people worldwide stutter, about 1% of the world's population. The impact of<unk>  on a person's functioning and emotional state can be severe. This may include fears of having to enunciate specific vowels or consonants, fears of being caught<unk>  in social situations, self-imposed isolation, anxiety, stress, shame, low self-esteem, being a possible target of bullying (especially in children), having to use word substitution and rearrange words in a sentence to hide<unk> , or a feeling of "loss of control" during speech.<unk>  is sometimes popularly seen as a symptom of anxiety, but there is no direct correlation in that direction.<unk>  is generally not a problem with the physical production of speech sounds or putting thoughts into words. Acute nervousness and stress are not thought to cause<unk> , but they can trigger<unk>  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) that reduce the amount of acute stress necessary to trigger<unk>  in any given person who stutters, worsening the situation in the manner of a positive feedback system; the name 'stuttered speech syndrome' has been proposed for this condition. Neither acute nor chronic stress, however, itself creates any predisposition to<unk> . The disorder is also variable, which means that in certain situations, such as talking on the telephone or in a large group, the<unk>  might be more severe or less, depending on whether or not the person who stutters is self-conscious about their<unk> . People who stutter often find that their<unk>  fluctuates and that they have "good" days, "bad" days and "stutter-free" days. The times in which their<unk>  fluctuates can be random. Although the exact etiology, or cause, of<unk>  is unknown, both genetics and neurophysiology are thought to contribute. There are many treatments and speech therapy techniques available that may help decrease speech disfluency in some people who stutter to the point where an untrained ear cannot identify a problem; however, there is essentially no cure for the disorder at present. The severity of the person's<unk>  would correspond to the amount of speech therapy needed to decrease disfluency. For severe<unk> , long-term therapy and hard work is required to decrease disfluency.
Stuttering
Hoarse voice
Drooling
Spasmodic dysphonia
Stilted speech
Facial toning
Kussmaul breathing
Sleepwalking