A common element in the immediate inducement of effortless, natural-sounding, fluent speech in people who stutter: 'the second speech signal'.

Recent attempts to find a common element in the inducement of fluent speech have focused on Wingate's notion that fluency can be induced via an altered manner of speaking by placing an emphasis on phonation. The problem with this notion of fluency enhancement is that it appears to be too expansive a scheme of fluency. The schemata allows for any forward flowing speech or speech-like act to be considered fluent despite the increased cognitive mediation, the extra effort involved in implementing the procedure, the unnaturalness of the resultant end product, and a lack of stability over time. It is proposed that the only significant characteristics of 'true fluency' are that it is indistinguishable from the typical fluent speech of people who do not stutter, and that it is effortless in nature. This is achieved via the use of a second speech signal which is not cognitive in nature, is operationally delineated, and is easy to manipulate.

Reduction of stuttering: the dual inhibition hypothesis.

Treatment for stuttering attempts to reduce or eliminate the observable core markers of the disorder, specifically repetitions and prolongation. In this hypothesis, it is proposed that stuttering may be inhibited by two distinct yet related procedures: active inhibition and passive inhibition. Active inhibition is brought about when the person who stutters makes volitional changes to his or her speaking pattern, such as when employing behavioral modification techniques. Passive inhibition automatically inhibits the involuntary stuttering block and can be induced from an external source, such as altered auditory feedback, or by the use of sufficient active inhibition. It is suggested that passively inhibiting stuttering results in speech that is more automatic, natural sounding, and truly fluent speech than the speech that is derived primarily from active inhibition. Evidence of passive inhibition resulting from active inhibition can be seen when people who stutter exhibit uncontrolled fluency following behavioral therapy.

Producing the vowel/a/ prior to speaking inhibits stuttering in adults in the English language.

This study investigated the effects of producing and listening to the vowel /a/ on the frequency of overt stuttering moments in eight people who stuttered. Stuttering frequency counts were made for the speech produced in the control condition, and after each of these four experimental conditions: (a) producing a vowel /a/ for 4 s; (b) producing a vowel /a/ for 4 s and waiting for 4 s; (c) listening to a recording of the vowel /a/ for 4 s; and (d) listening to a recording of the vowel /a/ for 4 s and waiting for 4 s. A significant reduction in the stuttering frequency was only observed following production of the vowel /a/ without a 4 s delay (P=0.02), suggesting that the vowel production prior to speech, serves as a temporary fluency enhancer. Its similarity to the occurrence of overt stuttering moments (e.g. discrete part-word repetitions and prolongation's) and its relationship to the fundamental nature of the pathology are discussed.

Stutter-free and stutter-filled speech signals and their role in stuttering amelioration for English speaking adults.

This study examined the power of an exogenously generated stuttered speech signal on stuttering frequency when compared to an exogenously generated normal speech signal. In addition, we examined the specific components of the second speech signal, which might be responsible for the inducement of fluency in people who stutter. Eight males and two females who stuttered participated in this study. Experiment I involved meaningful speech: normal continuous speech, normal interrupted speech, stuttered continuous speech, and stuttered interrupted speech, whereas Experiment II involved vowels and consonants: /a/, /a-i-u/, /s/, /s-sh-f/. The results indicated that stuttered and normal speech signals were equally effective in reducing stuttering frequency. Further, the vowels were more powerful than consonants in inducing fluency for people who stutter. It is suggested that acoustic manifestations of stuttering, rather than a problem, may be a natural compensatory mechanism to bypass or inhibit the 'involuntary block' at the neural level.