Stuttering (alalia syllabaris), also known as stammering (alalia literalis or anarthria literalis), is a speech disorder in which the flow of speech is disrupted by involuntary repetitions and prolongations of sounds, syllables, words or phrases, and involuntary silent pauses or blocks in which the stutterer is unable to produce sounds. The term stuttering is most commonly associated with involuntary sound repetition, but it also encompasses the abnormal hesitation or pausing before speech, referred to by stutterers as blocks, and the prolongation of certain sounds, usually vowels and semivowels...