Support for Speech Perception Interventions in Speech Therapy

I am writing a third blog on this strange experimental protocol in which the talker produces a syllable repeatedly and the talker’s speech output is altered in a systematic fashion so that the talker hears him or herself say something that does not correspond to their own articulatory gestures. I am fascinated by these experiments because they are a window onto feedback control which is essential for a successful speech therapy outcome. Initially in traditional speech therapy the SLP is providing a lot of external feedback about the child’s articulatory gestures (knowledge of performance feedback) and the correctness of the child’s speech output (knowledge of results feedback). But given that the SLP cannot follow the child around outside the clinic room, eventually the child must learn to use self-generated feedback for speech motor learning to occur. Can children use auditory feedback to change their own speech?

In a previous blog, On Birds and Speech Therapy, I discussed interesting work from Queen’s University  suggesting that toddlers do not use feedback control like adults do during speech motor learning.  These researchers found that adults will compensate for perturbations of their own speech by adjusting their articulation to get the desired auditory feedback. In contrast, very young children do not compensate in this way. I suggested that this may be because toddlers do not perceive speech with the same degree of precision as adults. This hypothesis was supported by another study in which speakers of French and English did not show the same compensation effect to a perturbation that made their vowels sound like a French vowel. The English talkers did not respond to a perturbation to which they were not perceptually sensitive (see Feedback Control and Speech Therapy Revisited).

Recently, I was delighted to find another study involving children provides even stronger confirmation that perceptual representations play a key role in the child’s ability to use feedback for speech motor learning. Shiller and Rochon (2014)  randomly assigned 5- to 7-year-old children with typical speech to two training conditions: the control group received speech perception training for the /b/-/d/ contrast; the experimental group received speech perception training for the /ɛ/-/æ/ contrast. Prior to and subsequent to this training both groups experienced the perturbation experiment: both groups repeated said “Beb” while their own speech was altered to sound more like “Bab”. Prior to perceptual training, both groups showed a small compensation for this perturbation in the feedback of their own speech. After speech perception training the experimental group showed twice as much compensation as before whereas the control group showed no change in the amount of compensation.  The results show that children can indeed use feedback for speech motor adaptation; furthermore, this ability improves as perceptual boundaries between phoneme categories become better defined —with age or with training.

The conclusions of the study are very gratifying. Citing my own work on the importance of speech perception training as a strategy to facilitate speech production learning by children with speech sound disorders, the authors conclude:

“The results of the present study complement this work nicely, demonstrating that improvements in children’s auditory perceptual abilities do not simply improve motor performance, but also alter the capacity for auditory-feedback based speech motor learning—a process that is central to the clinical treatment of speech production disorders.” (p. 1314)

No surprise that I like this study a lot!

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2 Comments

  1. I was at University when I first heard that intervention on perception could improve production. At first, not knowing everything I know now, I thaught it was a very strange idea.

    Now that I systematically assess children with DPD speech perception and stimulability, I am always surprise to see how many of them don’t hear the difference, for exemple, between /k/ and /t/, or can’t detect mistakes I make. It’s also a revelation for parents who see their child’s problem differently and understand why perception is important ! Children in my office usually like it ! They like to be the one to say if I’m saying ot right or not.

    I think intervention on perception can also be excellent for children who won’t repeat and who don’t accept “drill” approach. I’m wondering, do you think perception training could be effective on CAS also ? Or does CAS always require drill ?

    Reply
  2. Hello Marie-Pier, Thank you for your comment on this post. It is the most gratifying part of my career, to see the growing recognition of the importance of speech perception as a factor in speech delay! And in my case as in yours, starting with the experience of the children themselves. Francoise and I have published another randomized control trial, just posted in manuscript form today, showing that an approach that focuses primarily on listening skills but with very little production practice (a little bit of minimal pairs work at the end) can be very effective for children with developmental phonological disorders: A Randomized Trial of Twelve Week Interventions for the Treatment of Developmental Phonological Disorder in Francophone Children http://ajslp.pubs.asha.org/article.aspx?

    As for the children with CAS, it depends on how you define CAS – Tanya Matthews and I will present on this topic at ASHA this year. When the children present with transcoding errors on the Syllable Repetition Task, inconsistent errors, syllable segregation and prosody errors and poor performance on maximum performance tasks – in other words all the classic signs of dyspraxia, the children definitely benefit from what we call an auditory motor integration approach. Here the auditory perception work must be combined with very high intensity production practice. We also teach the child to self monitor and use delayed feedback as much as possible, encouraging the children to make those connections between their own speech gestures, the acoustic outcome and their intended targets in all sensory domains.

    There is another group of kids with inconsistent errors that has a phonological planning deficit however that does not benefit from this approach however – that is where it gets tricky.

    Susan

    Reply

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