A Theory of Stuttering
A Theory of Stuttering
A theory should explain the observable facts and relationships, but it should also enable us to derive testable predictions. The most important prediction that should follow from a theory of stuttering is how to treat it most effectively. If my theory is correct, the best treatment should be a change in the allocation of attention during speech. Below, I have outlined how this can be achieved. For the sake of conciseness, I put this in the form of recommendations for those affected, but note that it is derived only from my theory and my own experience as a stutterer. If you are affected, you can try it to see if it helps you.
1. Desensitization: Don’t think of stuttering when speaking, even not of listeners’ reactions to it, and don’t attempt to avoid or cover it. Accept the fact that your speech production system is susceptible to the kind of faults that cause stuttering (this doesn’t imply that you are forced to stutter at any certain moment).
2. Pausing: Plan your sentences incrementally, step by step, with pauses between clauses and units of meaning. Do not overly focus on formulation; speak spontaneously! Slips of the tongue, self-corrections, and pauses are part of spontaneous speech.
3. Attention to auditory feedback: Listen to your voice continuously, even at unstressed function words and at the ends of the words! If possible, peak in a powerful, sonorous voice and with expressive intonation! This supports attention to auditory feedback and can, besides, enhance your self-confidence (read more).
Briefly said, do not too much focus on speech planning, and listen to your voice when speaking. Speak spontaneously and do not try to avoid stuttering by voluntary control of articulation, phonation, or breathing, or by word substitution or reformulation.
I don’t think that current therapy programs are ineffective; the effectiveness of some of them was confirmed in studies (e.g., Euler et al., 2014; Ingham et al., 2015). However, the question is: why do these therapies work? This is, not least, a matter of theory, namely, of the theories behind therapies. Even if a therapy is effective, it does not follow that the underlying theory is correct.
For instance, in the Kassel Stuttering Therapy (the most advanced fluency-shaping program in Germany), prolonged speech, gentle voice onsets, and pausing are central. Using fMRI, Neumann et al. (2003) examined clients of the Kassel Stuttering Therapy before and after treatment. They found greater activations in several auditory cortical areas during overt reading after therapy as compared with before therapy. Even in a follow-up examination two years after therapy, the superior temporal gyrus (BA22) was significantly greater activated bilaterally during overt reading in the former clients, as a group, than before the therapy, although no effect on auditory behavior or auditory processing is intended with the Kassel Stuttering Therapy.
Likewise, greater activations in BA22 bilaterally were found during monologue in a group of clients who had completed the first phase of the Modified Phonation Interval (MPI) Therapy (Ingham et al., 2003). As with Kassel Stuttering Therapy, MPI does not aim to change auditory behavior or auditory processing. Hence, the question arises: Is it actually prolonged speech, gentle voice onset, or the avoidance of short-phonated intervals, respectively, that works in those therapies? Or could it be a change in auditory behavior and improved processing of auditory feedback?
The use of a fluency-shaping technique may influence auditory attention during speech and, by extension, the processing of auditory feedback. On the one hand, prolonged speech and particularly the prolongation of short-phonated intervals increase the temporal proportion of vocalized sounds (vowels and voiced consonants), and this may intensify the perception of one’s voice, by itself or because it sounds unfamiliar. Moreover, if all short-phonated intervals are avoided, all syllable starts are controlled by audio-phonatory coupling (read more), which ensures that speech motor control is closely linked to auditory feedback.
Gentle voice onset as well may draw the speaker’s attention to auditory feedback because it sounds unfamiliar. And although the technique is learned with the help of visual feedback, its application in everyday life requires auditory monitoring. These considerations are in accordance with Kell et al. (2018) who have, on the basis of neuroimaging data, assumed that fluency-shaping therapy may induce more efficient auditory-motor mapping.
In my view, gentle voice onset is not helpful in the treatment of stuttering because (1) it requires voluntary control of breathing (throttling exhalation), (2) it sounds unnatural, and (3) it is not necessary, since muscle tension is not the cause of stuttering, but a secondary behavior, a spontaneous reaction to the inhibition of speech flow.
Possibly, fluency-shaping techniques reduce stuttering not because of the altered manner of speaking itself, but rather because using these techniques connects speech motor control closer to auditory feedback.
Electronic speech aids based on delayed and frequency-altered auditory feedback can help practice and habituate listening to one’s voice when speaking. It is probably not a specific delay or frequency shift that (by an unknown, mysterious mechanism) reduces stuttering when such devices are used, but rather the simple fact that the altered auditory feedback sounds odd and draws the speaker’s attention to it. Unger, Glück, and Cholewa (2012) and Foundas et al. (2013) found a significant reduction of stuttering frequency even when the devices were used with delay and frequency shift switched off. This was probably because the slightly amplified and more direct auditory feedback through earphones was unfamilar and attracted attention.
A simple and inexpensive speech aid for children is the Toobaloo, a tube made from plastic with two curved, widened ends. It looks a bit like a telephone handset and “magnifies the voice, making it easier for students to hear the sounds that make up words (phonemes) as they learn to read, spell, or process language. In speech therapy, the Toobaloo’s auditory feedback helps improve articulation and phonology” (so the vendors). The Toobaloo is applied by therapists against auditory processing disorder (APD), dyslexia, and stuttering (see the videos below). The commercially available Toobaloo is made for children and a bit too small (too short) for adults. But in a DIY market, you will certainly find suitable waste pipe components that you can put together to a “speech flow pipe” for adults (see examples).
Another toy that may help stutterers improve their speaking is the Echo Mic, a passive resonator that mechanically generates an ‘echo’ of the user’s speech. Stuart et al. (1997) found that its use improved the speech fluency of adults who stutter, and again, the reason might be that the odd-sounding ‘echo’ drew their attention to auditory feedback.
Here are four videos about the Toobaloo and (the bottom one) about the Echo Mic:
Kalveram (1983) found that the duration of long syllables is controlled based on auditory feedback: the feedback of the start of a long syllable provides the information by which the brain determines the duration of that syllable and, with that, the start of the next following syllable. Kalveram called this mechanism ‘audio-phonatory coupling’ (see also Jäncke, 1989, 1991; Kalveram & Jäncke, 1989; Natke 1999).
Audio-phonatory coupling can work only in long syllables because the processing of auditory feedback takes too much time for controlling the duration of short syllablesy. Kalveram and his colleagues wrote of “long-stressed” syllables, but the essential thing is the length of the syllable (however, in German and other European languages, syllables are usually stressed by speaking them not only louder but longer).
Audio-phonatory coupling implies that the production of long syllables involves auditory feedback; only the production of short syllables does not. If all syllables of an utterance are long-spoken, as in slowed, prolonged speech, auditory feedback is permanently involved, such that speech control cannot decouple from it. This explains the strong fluency-enhancing effect of prolonged speech.
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The photos below show Toobaloos made and lovingly decorated by French teachers. (return)
