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!


Autism is a Neurodevelopmental Disorder: Do you know what that means?

Although this blog is devoted to the topic of developmental phonological disorders, readers who follow my tweet feed might notice that I retweet information about autism. I have a professional interest in autism because it falls into the category of neurodevelopmental disorder as does phonological disorder. I have a personal interest as well because I am a parent of a young person “on the spectrum” as we say — I don’t consider myself to be an expert on the science of autism but I have a certain expertise nonetheless.

As a parent I find the endless stream of articles describing “hopeful treatments” to be interesting and irritating at the same time. There have been many recently as randomized control trial methodology has become more common in the field. Medical Daily proclaims the “power of group therapy” describing Hardan et al’s study in the Journal of Child Psychology and Psychiatry. Descriptions of Amy Wetherby’s study go so far as to tell us that it is possible to “curb or stop the symptoms of autism”. There was wide dissemination of a Lancet study claiming that early intervention would prevent autism even though there were no statistically significant effects in this trial with infants whose risk of autism was somewhat uncertain.

Now, don’t get me wrong. I actually think that all of the treatments described here are very good treatments, the best we have at the moment. It is just that I can’t quite figure out what it is that the journalists and researchers and publishers think we should be hopeful for. What does it mean to “curb or stop autism symptoms” anyway? The articles and the press releases are all so carefully written that it is difficult to accuse anyone of overstating their claims but maybe we should be concerned about what is not said rather than parsing the modifiers that are interspersed with the claims that are made in the headlines.

So let me say what I think is missing from these press releases. The thing about autism is that it is a neurodevelopmental disorder. That means that autism is DEVELOPMENTAL – you can no more cure autism than you can cure neurotypical development. Every parent struggles to help their child meet the challenges of everyday life but in the case of autism the struggle is much, much harder. Why is it harder? Well, that’s the NEURO part. A really important concept in brain development is experience expectancy. The neurotypical brain develops in a way that allows it to learn from and adapt to the changing environment that the child encounters as it grows older. This brain development requires very specific inputs from that environment in order to develop in this way. The relationship between brain development and experience with the environment is completely interdependent. Children with autism do not experience the environment like other children however even when they receive typical environmental inputs; furthermore, their brains tend to not develop in ways that help the child adapt to the changing environments and new challenges that all children face as they grow older. All the way through development there are these mismatches between what the brain is prepared to handle, the environment that the person is experiencing and the developmental challenges that the person is expected to surmount.

The studies that are reported with such fanfare in the media report outcomes that are measured exactly at the end of interventions that last for a matter of months. I believe that they help the children cope with the current challenge and they probably help the child and parent prepare for the next one coming up. How much hope they should offer for the longer term future is questionable. For the parent participant I hope they show that if you can win one battle, you are likely to win the next one — as long as you can maintain your stamina there is hope there — but don’t let down your guard because there be dragons ahead!

Recently there was a study in the media that did address the developmental nature of autism: this Canadian study published in JAMA Psychiatry described trajectories for children between the ages of 4 and 6 for autism symptoms and adaptive functioning. It is fascinating because it suggests that the predictors of outcomes for autism symptoms may be biological (e.g., female sex) whereas the predictors of outcomes for adaptive function may be environmental (e.g., early diagnosis leading presumably to earlier intervention) although this is complete conjecture on my part. What the study does show clearly is that autism symptoms and adaptive function are not coupled together. What I have found as my daughter has become an adult is that she has absolutely no patience with any attempt to change her autism symptoms —she very aggressively expects the rest of the world to adapt to those! But she works actively to adapt to the environment to meet her own needs for work and companionship and an acceptable level of anxiety and in that she is very successful.