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!

Top down or bottom up target selection with toddlers?

A new paper on the consonant repertoires of toddlers confirms the close relationship between early speech and language development: Sotto, C. D., Redle, E., Bandaranayake, D., Neils-Strunjas, J., & Creaghead, N. A. (2014). Fricatives at 18 months as a measure for predicting vocabulary and grammar at 24 and 30 months. Journal of Communication Disorders, 49, 1-12. Specifically these authors examined the relationship between consonant repertoires at 18 months and performance on the MacArthur-Bates Communicative Development Inventories: Words & Sentences (MBCDI: WS) at 18, 24 and 30 months. Although inventory size was not significantly correlated with vocabulary size and use of grammatical markers at 24 and 30 months, the presence of fricatives in the inventory at 18 months was associated with higher mean scores on the 24 and 30 month language tests in comparison to language test performance for toddlers who did not produce fricatives at the earlier age. The discussion nicely covers the many intervening variables that might account for this relationship. (Clarification added in response to reader questions: the children in the study were normally developing).

I was pleasantly surprised to find that all the raw data is presented in the paper so that the consonant repertoires for each of the 37 toddlers at 18 months could be examined directly. This allowed me to check whether these repertoires conformed to the expectations of the implicational hierarchy as described by Dinnsen et al in an older paper (the hierarchy is derived from earlier work by Jacobson I believe): Dinnsen, D. A., Chin, S. B., Elbert, M., & Powell, T. W. (1990). Some constraints on functionally disordered phonologies: Phonetic inventories and phonotactics. Journal of Speech and Hearing Research, 33(1), 28-37. The hierarchy takes a structural approach assigning the child to different levels on the basis of the phonetic feature “contrasts” that are present in the phonetic repertoire as shown in the table below, keeping in mind that the child does not have to use the phones contrastively; there need be only representatives of the opposing feature classes present in the repertoire. The hierarchy is said to be implicational because if a child produces the feature attributed to one level of the hierarchy it is theoretically impossible for the feature contrasts at any lower level to not be present. Therefore the presence of voiced and voiceless phones (Level B) implies the presence of labial and coronal place as well as obstruent, glide and nasal manner features (Level A). I examined each of the repertoires in the Sotto et al paper and determined the highest level represented for each child and noted any violations of the expectation of the implicational hierarchy. The results are shown in the table below.

Implicational Hierarchy

I find it to be very interesting that one third of the toddlers in this study do not meet the assumptions of the implicational hierarchy. For example if we consider the children who produced a Level C phonetic repertoire, in other words, the 24 22/37 toddlers who produced fricatives and or affricates, we find that 6 of these did so despite lacking glides (4 children) or nasals (2 children) in the inventory. In Dinnsen et al, 40 preschoolers with speech sound disorders were described and the 1 child that failed to meet the implicational assumptions of the hierarchy was assumed to have a “deviant” phonology. However, (as I have suggested for Dodd’s so-called “deviant” categories as well), deviant behaviors have a funny way of showing up in very early language development.

What are the implications of these data and my re-analysis for speech and language therapy? To be honest I am not sure. One thing that I am quite sure of is that the findings do not support the “complexity” approach to target selection – the idea proposed in Dinnsen et al is that treating Level E phone contrasts will cause the lower level contrasts to appear is if by magic because of the internally specified implicational relationship between the contrasts as if they were all linked together like Christmas tree lights. I have shown that this approach does not in fact work (see Rvachew & Bernhard, 2010). This is not to say that one should take the opposite approach by structuring your treatment approach to introduce features in the opposite direction, working your way up the levels from A to B (and contrary to some myths in circulation I have never recommended this). I think that the important thing to keep in mind is that children at this stage of phonological development are developing their phonology and their lexicons so as to enhance lexical contrast  rather than phonological contrasts and therefore one needs to take a language based core vocabulary approach in any case.

The problem that I have is that I have never been comfortable with the idea of picking any words that are “functional” and teaching them even if the child hasn’t a hope of approximating the word (those poor children with speech problems named Clarence are fortunately few!). I prefer to take a systematic approach introducing new phones to maximize the probability of success and the implicational hierarchy shown above is maybe not a bad start if you have a child with no consonant repertoire at all (this does happen sometimes). Another possibility is Daniel Ling’s approach (teach all manner classes at once at one place of articulation and then move to the next place, leaving voice contrasts to the end). On the other hand, given the broad variety of strategies evidenced by the children in the Sotto et al study maybe the notion of taking any words that are important in the child’s environment is both ecologically and theoretically defensible. I will come back with some summaries of Dodd’s work on the core vocabulary approach another time but I think that this is a problem worthy of more rigorous and empirical study with larger samples!

Introduction to the Wait Times Benchmarks Project

1. Introduction to the Wait Times Benchmarks Project

Access to speech, language, swallowing and hearing services is a critical concern across Canada. One indicator of the urgency of the problem is lengthy waits for service after a need has been  identified in one of these areas. Of course this issue is not restricted to communication health as attested by the Wait Times Alliance.  The Alliance was formed by doctors in 2004 to provide solutions to the problem of long waits for medical care in Canada’s publicly funded health service. Sadly, long waits for speech, language and hearing services are not specific to Canada, as reports in Australia and the United Kingdom have highlighted similar concerns to those raised by families by of children and adults who need services in Canada.

Although access to service is a multifaceted problem there are many reasons that wait times in particular invite a common focus by clients, service providers, funders, and politicians as the essential issue to target for improvement. The recent report by the Wait Times Alliance (Time to Close the Gap, Wait Times Alliance, 2014) lists several:

  1. it is established that many other countries with universal health care have succeeded in providing timely access to service and therefore we should not tolerate long waits when they are clearly not necessary;
  2. it can be shown that long waits for necessary services impose a significant burden on patients who are waiting as well as on society in general; and
  3. long waits for service impair health system performance such that improvements to wait times should result in gains for the system as a whole.

These considerations are as crucial for speech, language, swallowing and hearing health as for any other sector of the health care system. One step toward improvements in wait times is the development of benchmarks that indicate the maximum time that an individual should wait for service after taking into account the likelihood of significant clinical consequences should the wait  be longer. The Pan Canadian Alliance of Speech-Language Pathology and Audiology Organizations has committed to establishing reasonable wait times benchmarks as the first step toward reducing wait times for services.  A series of ad hoc committees recommended benchmark wait times for different diagnostic categories (see the Speech-Language and Audiology Canada (SAC) website). These wait times are being reviewed and reformatted according to a standard template and released publicly to the clinical community one at a time along with a published paper that provides the scientific foundation for each benchmark. The Benchmark Wait Times for Pediatric Speech Sound Disorders was released at the SAC Conference in May 2014 _and the associated Report was published in CJSLPA in Spring 2014 .The revised Benchmarks for Pediatric Language Disorders will be released soon and the Benchmarks for Fluency disorders are in progress.

In addition to releasing the benchmarks and the associated scientific reports, SAC will be providing additional information about benchmarks and their use in this blog which will be cross-posted to the SAC website and developmentalphonologicaldisorders.wordpress.ca. We will be inviting feedback and participation from the SAC membership or other interested commenters with each release. The schedule of upcoming blogs is shown below. We hope that you will follow the blog and consider commenting or contributing to this conversation.

Upcoming Posts

2. What is a Benchmark?

3. Approaches to Developing Wait Times Benchmarks

4. Evidence Based but not Evidence Bound

5. Use of Benchmarks by Clinicians and Policy Makers

6. Potential Advantages of Having Wait Times Benchmarks

7. Potential Disadvantages of Having Wait Times Benchmarks

8. Strategies for Achieving Wait Times Benchmarks

9. Factors that Impact on the Achievement of Wait Times Benchmarks

10. Role of the Pan Canadian Alliance and SAC in the Achievement of Wait Times Benchmarks

Wait Times Benchmarks for Speech-Language and Hearing Services

An important statement in the Universal Declaration of Communication Rights (International Communication Project 2014) is “We believe that people with communication disabilities should have access to the support they need to realize their full potential”. Even in those countries where speech-language pathology and audiology services are well established, long waits for service can be a significant barrier to communication for many children and adults. Twitter is a powerful tool for sharing knowledge and strategies for problem solving. This week on @WeSpeechies (see WESPEECHIES) we can share international perspectives on perceived appropriate wait times, actual wait times and strategies for reducing wait times for services around the world. When sharing information about this topic please identify yourself and provide general information about the nature of your clients and service sector while respecting privacy and confidentiality of specific individuals and organizations.

Questions
Q1. Approximately how long do your clients with speech-language needs wait for services? #WeSpeechies
Q2. Do you work with established expectations for wait times? How were the wait time benchmarks determined? #WeSpeechies
Q3. Do you think that clients with speech-language needs should have a guaranteed wait time for service? #WeSpeechies
Q4. What kind of criteria for deciding who gets served first are most fair? #WeSpeechies

Dose Frequency for Effective Speech Therapy

I am writing to address a specific question that has come up: in order to be effective when treating an “articulation disorder” how many trials should the SLP elicit from the client per treatment session? This is an important question and it is surprising that so little research attention has been directed at uncovering the answer. This is a question about what Warren, Fey and Yoder (2007) refer to as “dose: number of properly implemented teaching episodes per session”. We could be talking about the number of presentations of a model or perceptual responses by the child when conducting an “input oriented intervention” but in this blog I will restrict my comments to those interventions that are focused on obtaining speech responses from the child and therefore the teaching episode involves practicing a speech behavior such as a sound, syllable, word or phrase and each elicitation is counted as a single dose. In speech therapy the question of optimum dose frequency (how many trials per session of a given length) comes up most often in the context of Childhood Apraxia of Speech (CAS) where it is generally believed that practice intensity is particularly important. Recently, Murray, McCabe & Ballard (2014) reported that studies on approaches for CAS typically involved 60 to 120 trials per session whereas studies on approaches for phonological disorders typically involved 10 to 30 trials per session. The closest I have seen to an experimental investigation of dose frequency is the single subject experiments conducted by Edeal and Gildersleeve-Neuman (2011) in which low intensity (30 to 40 trials/session) versus high intensity treatment (100+ trials/session) was compared within two children with CAS. They concluded that “Both children showed improvement on all targets; however, the targets with the higher production frequency treatment were acquired faster, evidenced by better in-session performance and greater generalization to untrained probes.”

I don’t see any reason why a higher intensity intervention would not also be a “good thing” when treating children with a phonological disorder and indeed this is what Williams (2012) concluded when she reviewed data from her lab. After a quantitative summary of treatment outcomes for 22 children who received her multiple oppositions intervention she recommended a minimum dose of 50 trials over 30 sessions with anything less being ineffective and higher doses (70 trials or more) being necessary for the most severely impaired children. In this case the children received 30 minute sessions twice per week.

Recently we have been conducting single subject experiments with children who have CAS and although treatment intensity is not the primary focus of attention in these studies my doctoral student, Tanya Matthews, and I have been looking at the relationship between dose frequency and outcomes. In the figures shown below the children’s “next day probe scores” (an indicator of maintenance of learning over a short-term period, expressed as proportion correct) are shown as a function of the number of trials completed (top chart) as well as the number of correct trials in each session (bottom chart). There is not much variability in the number of trials per session because we put a lot of pressure on the student SLPs to keep this number high. However the number of correct trials varies quite a bit depending upon the severity of the child’s speech delay and whether it is early or late in the child’s treatment program. The lower chart shows that next day probe scores are better if the number of correct trials in each 20 minute practice session is above 60. The number of correct trials never goes above 80 because we are working to keep the child “at challenge point” so if the child begins to produce more than 80% correct trials we make the task more difficult. However, if the child is producing many errors it does not really help to keep the response rate high either because the child is just practicing the wrong response anyway.

So to sum up, notwithstanding the rather poor quality and quantity of the data, my impression is that dose counts: regardless of whether the child has a motor speech disorder or a phonological disorder it is important to achieve as many practice trials as you can in a treatment session but it is also a good idea to ensure that the child is achieving accuracy at the highest possible level of complexity and variability during practice as well.

Number of trials by probe score

Phonological Memory and Phonological Planning

I have been writing about the children in our intervention study for children with Childhood Apraxia of Speech (CAS). So far about half of the children referred to us appear to have difficulties in the domain of phonological memory with their overt phenotype corresponding to the subtype described by Dorothy Bishop Dodd as Inconsistent Deviant Disorder. Shriberg et al. (2012) have developed the Syllable Repetition Task as one means of identifying deficits in “memory processes that store and retrieve [phonemic, sublexical, and lexical] representations. We have been using this SRT test to differentiate children who have deficits in phonological planning versus motor planning. I described the profile that corresponds to difficulties with motor planning (transcoding) in a previous post. Today I will discuss the phonological memory or phonological planning profile that we see in approximately half of the children that are referred to us with suspected CAS.

These children can be identified by a qualitative analysis of their SRT performance and by their performance on the Inconsistency Test of the DEAP. Starting with the SRT, one child in our study for example was able to achieve 12/18 consonants correct when imitating 2-syllable items but only 5/18 consonants correct when imitating 3-syllable items, thus exemplifying the classic profile of a child with phonological memory difficulties – better nonword repetition performance for short versus long items. Qualitatively he tended toward consonant harmony errors even with some 2-syllable items, /bama/=[mama],  /maba/=[mama],  and then more frequently with the 3-syllable items, /nabada/=[mamada]. Addition of syllables and vowel errors also occurred, /manaba/ = [mamadada],  /manabada/=[mimadama]. Poor maintenance of phonotactic structure and vowel errors were also observed on the Inconsistency Test, “helicopter” = [hokopapɚ], “elephant”= [ɛmpɩnt], which yielded an overall inconsistency score of 78% as many words were produced with multiple variants, e.g., “butterfly”= [bʌtfaɩ], [bʌtwaɩ], [bʌtətwaɩ].

The most striking illustration of the difficulties these children have with the storage and retrieval of phonological representations comes during our treatment sessions however. In this research program we are teaching the children nonsense words in meaningful contexts. For example in one scenario we teach the children the names of “alien flowers” and in one of the treatment conditions we use graphic stimuli, paired with gestural cues if necessary, to represent the syllables and phonemes in the words and phrases that we are teaching. Many of the children in our study learn all of the nonsense words without difficulty (5 words per goal/condition introduced over 6 45-minute sessions). However children with the phonological memory difficulties have great difficulty learning the words (SLP: This is a speet. Say speet. Child: speet. That’s right, speet. What is it? Child: I don’t know. SLP: Yes, you do it’s speet, the purple one, the purple one is speet, remember, say speet. Child: ‘speet’. SLP, you’ve got it, the purple flower is speet, it’s a speet, what is it, it’s a … Child: um, I don’t know, and so on).

Image

The most effective intervention to use with these children closely mirrors the procedures described by Barbara Dodd as the “core vocabulary” approach and demonstrated by Sharon Crosbie in the video that accompanies their chapter in the Williams, McLeod and McCauley (2010) book. The video is lovely and shows how to use graphic stimuli and a chaining procedure to teach the child to produce a word consistently – the idea is to encourage the child to develop and implement their own phonological/motor plan rather than relying on an imitative model. The children respond to this technique really well and will learn to say the new words such as “speet” and “stoon” quickly and accurately. The trouble begins when our student SLPs want the children to use the new words spontaneously in phrases (e.g., “water the speet”). They have great difficulty remembering the word or even the carrier phrase without the imitative model and I have to work really hard to teach the student clinicians to withhold the imitative model in favour of using other cues to stimulate spontaneous production of the target words and phrases (SLP: What is it? Let’s start with the snake sound here…).

We have wonderful video of student SLPs learning these techniques as well as children achieving their goals. Tanya Matthews and I will be presenting them at ASHA 2014. The difference in the way that you implement therapy with these children is subtle but important. I am pretty sure that Case Study 8-4 in our book had a phonological planning deficit rather than the motor planning disorder that he was treated for. I can’t help but think that if he was treated with these techniques he might have made some progress in the three years that we followed his case (whereas he made literally no progress at all until he was treated with a synthetic phonics approach in second grade). I’d love to hear from you if you have any other ideas about how best to treat children with phonological memory problems and inconsistent deviant disorder.

 

 

 

Auditory Motor Integration Intervention for CAS

In March 2013 I described the research we are conducting in my lab to identify individual differences in response to two different approaches to the treatment of Childhood Apraxia of Speech. I also described the unique single subject randomization design that we are using and presented some data for one child without revealing the interventions that corresponded to the condition that worked best for this particular child. We have subsequently replicated this result with another child so today I am going to write about the features of the intervention that children with difficulties in the area of transcoding appear to benefit from most clearly. Recall that transcoding is revealed in part by addition errors on the Syllable Repetition Task. In the case of the child profiled in the previous blog, he added nasal consonants at syllable boundaries when asked to repeat the syllable strings and he was just as likely to do this for short strings as for long, e.g., “mada” → [bᴂndə] and “manabada” → [mandabad]. This child also had difficulty with multisyllable repetition during the maximum performance tests but no difficulty with the single syllable diadochokinetic rate. Within word inconsistency was borderline with inconsistent word productions largely reflecting single feature errors (voicing errors for example). Altogether the impression is of a true apraxia or motor planning disorder (as opposed to a phonological planning deficit, a more common problem that I will describe in a future post). Thus far we have assessed 18 children in this study and remarkably only 3 have presented with this particular profile.

Two of these children have shown the best response to an intervention that is directed at promoting auditory-motor integration. It includes input-oriented procedures that are described in Chapter 9 of my book combined with output-oriented procedures described in Chapter 10. The procedures are used to promote the consistent use of stimulable phonemes in the context of word shapes that are difficult for the child so that the focus is more on holistic movement patterns at the whole word level than on individual phonemes. In the case described here we taught novel “monster names” that had a strong-weak-strong stress pattern and word internal coda consonants such as “Biftenope” and “Hapnidreem” and assessed for carry-over to phrases with similar structures (pumpkin pie, bat mobile). 

One reason that we designed an intervention approach that focused on auditory-motor integration is that there is evidence from the animal literature suggesting that this might be a foundational problem in the case of apraxia. Kurt, Fisher and Ehret examined sensory-motor association learning in mice with two different FoxP2 mutations. The task involved learning to avoid electronic shock by leaping a hurdle (or not) to the other compartment of a box in response to varied tones that signaled the location of the shock. Mice with either mutation were impaired in their response, one more severe that the other, in comparison to wild-type mice that learned the task without difficulty. The second reason that we designed an intervention with an auditory-motor integration component is that the ability to modify motor plans in response to auditory feedback and in relation to an auditory target is theoretically essential to the acquisition of speech motor control.

So what does an intervention that focuses on auditory-motor integration look like? Not surprisingly it has procedures that focus attention on the auditory-perceptual aspects of speech as well as procedures that focus on motor practice, none of the procedures themselves being novel or surprising. During the prepractice portion of each treatment we ensured that the child had a good perceptual representation for the target words using auditory bombardment and focused stimulation in meaningful contexts as well as error detection tasks as described in my teaching blog (scroll down to week 22). We also taught the child to monitor his own speech and respond differentially to his own correct or incorrect productions of the target words. For example an appropriate activity might be for the child “call” the monster and to then place the monster in his sleeping bag in the tent if he heard himself produce the name correctly or to place the monster in an alternative sleeping bag out in the rain if he heard himself produce the name incorrectly (our students are endlessly creative and this variation on the game has proved to be popular with the children this year).  The practice part of the session, for the most part, proceeds as one would expect for any child with CAS, focusing on high intensity practice while the SLP provides just enough stimulation prior to each attempt to elicit a correct response more often than not. However, every effort is made to avoid providing too much feedback. Working in blocks of five trials each, summative knowledge of results is provided whenever possible – this means that the child is given an opportunity to evaluate his own responses in relation to his own auditory goal without interference from SLP input, and then compare his own judgment with the SLPs count of correct responses at the end of each 5 trial run. Edy Strand writes about the importance of giving the child time to integrate feedback in her chapter with Derbertine in Caruso and Strand (1999) and describes precisely how to do this. Given a high rate of responses (over 100 trials per 20 minute practice session) and an average of 70% correct responses, this child was able to make excellent progress as measured by both same day and next day probes (see green bars on his chart here). A second child with the same profile also showed a significant benefit in favour of this approach. A third child is still being treated and it will be some time before we will know if he completes the protocol and then many more months before blind coding of his results will be finished. But, we are hopeful!

Feedback Control and Speech Therapy Revisited

In August 2012 I posted a comment about MacDonald, E. N., Johnson, E. K., Forsyth, J., Plante, P., & Munhall, K. G. (2012). Children’s development of self-regulation in speech production. Current Biology, 22, 113-117. (see On Birds and Speech Therapy). In this paper the authors reported that toddlers did not compensate for perturbations of their own vowel formants and they concluded that toddlers “do not monitor their own voice when speaking in the same way as adults do”. I was skeptical of this claim since it is hard to imagine how children learn to talk at all if they do not have access to feedback control mechanisms. I suggested that perceptual explanations would make more sense and now there is published evidence that this is indeed the case, interestingly from a paper including Munhall as author, specifically, Mitsuya, T., Samson, F., Ménard, L., & Munhall, K. (2013). Language dependent vowel representation in speech production. Journal of the Acoustical Society of America, 133, 2993-3003.

The paper is fascinating because it shows that English and French talkers to not show the same compensation effect when participating in this experimental paradigm and when the vowels involve French rounded vowel categories (i.e., English talkers do not change their own speech to compensate to a perturbation that makes their own speech sound more like a French vowel whereas French speakers do). Furthermore, the amount of compensation that a talker produces is related to the talker’s underlying phonological representation of the vowel space, as represented in acoustic-phonetic terms. In this study, when the English listeners did not respond to the particular perturbation of their vowel formants that was used, the researchers did not conclude that English people are incapable of using feedback control mechanisms! Rather they concluded that “the function of error reduction itself appears to be language universal, while detection of error is language specific.” However, the use of feedback for error reduction is dependent upon the talker’s perception of the feedback which in turn is related to the listener’s phonological representations (previously this was not clear because the research participants are not always consciously aware of the way that the experimenters are manipulating their speech).

Obviously the same logic should be applied to the toddlers’ apparent failure to use feedback control in a similar experimental manipulation in which the toddler’s speech was changed from one English vowel to sound a little bit more like another English vowel. In fact, a perceptually motivated interpretation is favoured in Mitsuya et al.; when referring back to McDonald et al. they say “a stable phonemic representation is required for error detection and correction in speech, and sometime between 2 and 4 yr of age such a representation emerges and stabilizes.” This is not the interpretation that made the headline in Science Daily but it is the conclusion that makes more sense to me.

What are the implications for speech therapy? The research clearly supports my view that it is essential to ensure that your clients with speech sound errors have stable perceptual and phonological representations – this is a critical component of a treatment program aimed at establishing speech motor control and speech articulation accuracy As Mitsuya et al suggest, the acoustic target for speech is not just the phonetic category itself but the target category in relation to its neighbors. The treatment approach that I have always advocated is focused on phonemic perception: the important procedures include presenting the child with a large population of variable exemplars of the target category. These exemplars should identify the centre of the category, highlighting the important cues and the prototypical characteristics, while also allowing the child to explore the edges of the category so that the child can experience it in relation to similar but contrasting categories. Thus SAILS  presents the child with a task in which highly variable stimuli are judged to be the TARGET or NOT THE TARGET and some of the stimuli are rather ambiguous. SLPs do not always like the fact that not all of the stimuli are prototypical exemplars of the target category but in fact this amount of variability is important for the establishment of phonological representations. Mitsuya et al.’s paper is important because it reinforces the point that stable acoustic-phonetic representations for speech targets are essential for the use of feedback control in speech motor learning.

Conversations with SLPs (2)

Some of you know that SAILS, my speech perception intervention software, is available for free to any speech therapist working with children who speak a North American dialect of English. The license is available from McGill University and I receive many requests every week along with some feedback and questions from users.  Gissella wrote to me with the following interesting question and I would like to share it and the answer with my readers:

“I am currently using the SAILS program with some children and have found it very helpful. I was wondering if the program could be used by parents with the help (training and treatment) of the treating S-LP. If that is possible, how would the parent go around getting the software.”

I answered that I am not comfortable with releasing the licence directly to parents because I would prefer that the parent be working under the guidance of an SLP so the best thing is for the SLP to apply for the license on behalf of the parent via flintbox .  (By the way I have worked out a way to make this old software run on 64-bit computers – you can download instructions in the revised BACKGROUNDER from the flintbox site. The tablet app is still under construction but I am hopeful that it will be available in 2014).

Further to the topic of parent application of SAILS, I also sent Gissella a copy of my paper – Rvachew, Nowak, & Cloutier (2004) – describing a randomized control trial in which we taught parents to administer SAILS to their children in the clinic, after their child’s regularly scheduled speech therapy session. Children in the control group played with Living Books after their speech therapy session and their parent asked them questions about the story according to sImagecripts that we provided. Both groups showed similar gains in phonological awareness but the SAILS (Sp Percn) group made dramatically better improvements in articulation accuracy as measured by number of errors on the Goldman-Fristoe Test of Articulation (see Figure inserted into this post) and by Percent Consonants Correct as reported in the paper. In that study we didn’t send SAILS home with the parents – as Gissella commented in a subsequent e-mail: “I now realize that the frequency of once per week seems to be sufficient, and therefore it can be done within the clinic most of the time, no need for the parent to do this at home.” This is absolutely correct, in all of my studies we have found that the intensity of the speech perception intervention does not have to be that great – a 20 minute session once per week during the first three sessions on a new phoneme works just fine.

In a follow-up e-mail, Gissella had another really interesting question however; “often times parents ask if they can have this program at home as they see it is easy to use and enjoyable for the child. There has been one case where we had treated the phonological delay, but there was residual articulation (frontal lisp) that will be treated at a later time. The parent had seen how SAILS worked for the phonology part and was interested in continuing exposing the child to the samples for /s/.”  I think that this would be a really interesting application for SAILS but unfortunately there is no empirical evidence to prove that this would be effective. I have always wanted to do a randomized control trial in which children with residual errors in kindergarten were treated with SAILS and then measures of speech accuracy, functional communication and psychosocial outcomes were collected at 6-month intervals for the next two years. Would we see more cases of “spontaneous” resolution of the residual errors in the SAILS group than in the control group? Unfortunately I can’t get decent funding for randomized control trials that involve even children with severe speech sound disorders so I doubt that I could get enough funding for something like this (to have enough statistical power it would have to be a big multisite study with a lot of funding even though 18 percent of 8 year olds can be expected to have speech errors; see Roulstone et al., 2009). You cannot believe how often other researchers, even those working in the field of speech sound disorders, tell me that this most common of neurodevelopmental disorders is just “not important” (see Bishop, 2010)!

Online Gaming and Speech Therapy

I have just read this marvelous paper tweeted out by @vaughanbell: Stafford, T., & Dewar, M. (2013). Tracing the Trajectory of Skill Learning With a Very Large Sample of Online Game Players. Psychological Science. He was impressed by the very large sample size (N = 854,064) but I am impressed by the relevance of this paper for speech therapy. The researchers used “detailed records of practice activity from an on-line game” and used it to test hypotheses about learning in the game which requires “rapid perceptual decision making and motor responses”. Gratifyingly for us as speech-language pathologists, the results confirm the principles of motor learning that are currently promoted for successful treatment of childhood apraxia of speech (CAS), specifically practice intensity, distributed practice and variable practice conditions (for application of these principles to the treatment of apraxia of speech see for example Gildersleeve-Neuman in the ASHA Leader or Tricia McCabe’s ReST program).

There was one concept raised in the paper that was a little bit novel with respect to the CAS literature however: specifically, the authors talk about the “exploration/exploitation” dilemma. In the context of this simple but bizarrely fun computer game (found here at The Welcome Collection)  you can explore the axon growing environment when first learning to play or you can settle into a strategy of simply clicking on the closest protein in your circle of influence. The latter strategy will work to grow your axon which is the object of the game but you will miss out on learning how to maneuver your circle of influence so as to actively find the “power proteins” that advance the growth of your axon. Exploration has a cost in that it leads to more variable performance early on but the benefit is potentially better performance with longer experience. In fact, Stafford et al. observed a close relationship between higher early variance in performance and better performance during later attempts. This trade-off between exploration and exploitation reminded me of the importance of the expansion stage in early speech development and the implications for intervention with young children with CAS.

In Table 10-1 of Developmental Phonological Disorders: Foundations of Clinical Practice we suggest learning outcomes and therapeutic strategies to correspond to four stages of speech development as follows: 1. Expansion stage (explore possibilities of the vocal system); 2. Babbling and integrative stage (controlled variability); 3. Early speech development (expanding repertoire of phones and word shapes to achieve intelligible speech); and 4. Late speech development (ongoing refinements to achieve adultlike speech accuracy and precision). These stages are described in greater detail in Chapter 3 which covers the literature on the development of speech motor control. The expansion stage typically occurs during months 3 through 6 and is characterized by a variety of vocalizations that are not very speech-like (squeals, growls, raspberries and so on) as well as the appearance of fully resonant vowels and marginal babble. It is my experience that SLPs do not appreciate the importance of the expansion stage to normal speech development or understand its significance when planning an intervention program for children with limited if any speech capacity. Therefore I highlight this point in Chapter 10, as follows:

“The importance of the expansion stage in the laying of building blocks for later speech development is easy to forget when choosing goals for speech therapy, a topic to which we return shortly. Another important achievement during the infant period is the acquisition of canonical syllables when the child learns to control the variable parameters explored during the expansion stage, coordinating them to produce well-formed syllables in the context of babble, jargon, and early words. …Typical descriptions of speech acquisition focus on reductions in variability with age. … Therefore, it is not surprising that traditional speech therapy procedures are designed to enhance consistency and reduce variability in the production of phonemes with practice. However, variability is not always an impediment to speech learning and children with DPD often suffer from insufficient variability in their repertoire of speech behaviors. Performance variability can be viewed as facilitating, detrimental, or irrelevant to a successful outcome depending on the motor learning context (Vereijken, 2010). For example, the highly variable vocalizations of the expansion stage provide a complex foundation for the emergence of speechlike vocalizations at later stages. Infants who are described as being “quiet” during the first year of life lack sufficient variability for normal motor speech development. The normally developing infant harnesses rather than reduces this variability to coordinate the separate respiratory, phonatory, resonance, and articulatory components to produce babble in the next stage. Throughout the next 16 or so years there will be a continual interplay between adaptive variability to meet new challenges and increased stability to enhance precision. (p. 758)”

 I often talk to SLPs who are frustrated by failed efforts to teach new phones via imitation to children with severe speech sound disorders. However children with limited vocal repertoires must first be encouraged to freely explore their vocal systems. I describe procedures to encourage vocal play in detail in the book, following Dethorne, Johnson, Walder, and Mahurin-Smith (2009) and supplementing with examples of implementation from my own clinical experience. I hope that Stafford et al.’s interesting research and this amusing little game leads to more reflection about the role of exploration and variability in speech motor learning.

Follow

Get every new post delivered to your Inbox.

Join 117 other followers