Effective Interventions for the Treatment of Speech Sound Disorders
Children with a primary Speech Sound Disorder (SSD) make more errors in pronunciation than expected for their age, and the errors are not caused by other disorders such as hearing impairment,
(Shriberg, Austin, Lewis, McSweeney, & Wilson, 1997). Children with this kind of speech problem should be treated by a speech-language pathologist (SLP). Most of the children who are treated by SLPs have some form of SSD (Broomfield & Dodd, 2004). SSDs develop during childhood and can persist for many years after diagnosis (Law, Boyle, Harris, Harkness, & Nye, 2000). Children with an SSD are at-risk for social problems and are often bullied at school (Silverman, 1992; Hall, 1991). They may also have trouble at school because of poor
and weak reading skills (Catts, 1993; Raitano, Pennington, Tunick, Boada, & Shriberg, 2004; Rvachew, Ohberg, Grawburg, & Heyding, 2003; Rvachew & Grawburg, 2006; Lewis, Freebairn & Taylor, 2000; Webster & Plante, 1992; Webster, Plante & Couvillion, 1997; Bird, Bishop, & Freeman, 1995; Shriberg & Kwiatkowski, 1988; Larrivee & Catts, 1999). In turn, these difficulties have an impact on employment opportunities in adulthood (Felsenfeld, Broen, & McGue, 1994). Given the social and economic cost of speech difficulties for individuals with SSD and society at large, it is important to identify the most effective and efficient speech therapy practices for the treatment of SSD.
1. Is speech therapy effective?
2. What are evidence-based practices in speech therapy?
3. How much speech therapy is required for a good outcome?
1. Is speech therapy effective?
Carefully controlled studies that have been conducted in research settings show that speech therapy is effective: children who receive speech therapy improve their pronunciation skills faster than children who do not (Law, Garrett, & Nye, 2003). Unfortunately, at least one study of the effectiveness of speech therapy offered in community clinic environments has suggested that speech therapy is not always effective: children who received therapy in community clinics in this U.K. study did not improve faster than children who were simply monitored without actually receiving treatment (Glogowska, Roulstone, Enderby, & Peters, 2000). A recent study funded by the Canadian Language and Literacy Research Network followed children who received speech therapy at age 4 until the end of first grade. Most of these children began school with ongoing speech problems: only 15% recovered from their speech problem before starting kindergarten (Rvachew & Grawburg, 2006) and only 25% recovered before Grade 1 entry (Rvachew, Chiang, & Evans, 2007). In fact, half of the children who received speech therapy as preschoolers continued to show speech delay at the end of first grade (Rvachew, 2007). Research-based speech therapy may be more effective because these programs tend to be more structured, theoretically coherent and intense than clinic programs which tend to be more eclectic (Weston & Bain, 2003; Joffe & Pring, 2008). For example, the children who were involved in the U.K. study mentioned above received only 6 hours of treatment on average (Law & Conti-Ramsden, 2000).
2. What are evidence-based practices in speech therapy?
Imagine a child who says ‘doe’ in place of ‘soap’, ‘dee’ in place of ‘sleep’, ‘da’ in place of ‘clock’, and ‘mee’ in place of ‘meet’. In just four words the child has mispronounced the sounds ‘s’, ‘l’, ‘p’, ‘k’ and ‘t’. The first decision that the speech-language pathologist must make is which sounds to teach and in which order to teach them. Following the traditional articulation therapy approach, the SLP would work on one sound at a time, perhaps teaching the ‘p’ sound until it has been mastered and then moving on to a new sound. More recent phonological approaches address the child’s phonological system by working on patterns of pronunciation errors: for example, the SLP could begin by teaching the child to put the ending sounds on words, working on words like ‘beet’, ‘peep’, and ‘puff’ all at the same time. Very little research has compared these two approaches directly but it does appear that the decision to work on patterns of speech errors is more efficient and effective than teaching sounds one at a time (Major & Bernhardt, 1998; Pamplona, Ysunza, & Espinoza, 1999; Almost & Rosenbaum, 1998; Bernhardt & Major, 2005; Hodson & Paden, 1983). Research also suggests that it is best to begin with the easier sounds first (Rvachew & Nowak, 2001; Rvachew & Nowak, 2003). For example, it would usually be better to begin with ‘p’ and ‘k’, rather than ‘s’ and ‘l’. However, in rare cases it does make sense to begin with the most difficult sounds first, especially when the easier sounds seem to be improving spontaneously (Rvachew, 2005a).
One very important step in speech therapy that is often left out is to teach the child to hear the difference between the correct sound and the error sound. A computer-based treatment program has been developed for this purpose (Speech Assessment and Interactive Learning System; SAILS). The child listens to recordings of other children saying words. Our hypothetical child might listen to recordings of the word ‘soap’ and pick out the ones that sound like ‘soap’ and reject the ones that sound like ‘dope’. Several different studies have shown that this
speech perception intervention
is very effective with preschool aged children. When children are taught how to listen to a new speech sound as well as how to say the new speech sound, they progress twice as fast as when the treatment program focuses only on correct pronunciation (Rvachew, 1994; Rvachew, Rafaat, & Martin, 1999; Rvachew, Nowak, & Cloutier, 2004; Jamieson & Rvachew, 1992).
Phonetic placementhas been shown to be effective for teaching a child how to say a new sound (Powell, Elbert, Miccio, Strike-Roussos, & Brasseur, 1998). This involves the use of mirrors, imitative models, verbal instructions, and tools such as tongue depressors and straws to help children achieve correct placement of the articulators for production of new speech sounds. Phonetic placement should not be confused with
oral motor exercises
that target strength, speed, and range of motion of the articulators when producing movements outside of a speech context. There is no evidence that these oral motor exercises are effective and some evidence that they are unnecessary if not potentially counter-productive(Forrest, 2002; Guistin Braisliin & Cascella, 2005). For example, if the child does not know how to say the ‘oo’ sound it will probably not help to teach the child to blow bubbles through a bubble wand. It would be better to encourage the child to imitate ‘oo’, ‘boo’, and ‘too’ while looking in a mirror.
New technologies have also been developed to provide visual feedback to children during articulation practice. Electropalatography (EPG) provides a computer display of the position and timing of tongue contacts with a custom-made artificial palate into which a row of electrodes is embedded (Dent, Gibbon, & Hardcastle, 1995; Gibbon, Stewart, & Hardcastle, 1999; Gibbon, 1999; Gibbon, Hardcastle, & Dent, 1995; Dagenais, Critz-Crosby, & Adams, 1994). Ultrasound can also be used to show the position and shape of the tongue inside the mouth (Bernhadt, 2004; Bernhardt, Gick, Bacsfalvi, & Adler-Bock, 2005). Finally, spectrographic analysis displays visual information about the acoustic characteristics of speech (Masterson & Rvachew, 1999; Shuster, Ruscello, & Toth, 1995). A number of case studies have reported encouraging results with these devices but their efficacy has not been directly compared to the efficacy of more traditional procedures.
Meaningful minimal pair activities can be used to help the child discover the communicative function of different speech sounds. For example, an activity may be designed in which the child must make requests involving the words ‘bee’ and ‘beet’. If the child wants the ‘beet’ it is necessary to remember to add the sound at the end of the word. During this activity the child is naturally rewarded for using the correct speech sounds when the listener understands the message. This approach was shown to be effective in a study using a single-subject research design (Weiner, 1981). However, this procedure may not be effective unless the clinician first ensures that the child can hear the difference between the error and the correct form and has at least some understanding of how to produce the target sound correctly (Rvachew, 2005b). Another study found that 60% of children generalize correct production of new speech sounds to untaught words after being taught only a few word pairs with this approach (Elbert, Powell, & Swartzlander, 1991). This procedure is very consistent with the phonological approach to intervention and is usually included in the context of comprehensive packaged approaches to phonological therapy (Dean & Howell, 1986; Williams, 2010; Hodson, 2007).
Children with SSDs are at a very high risk for concomitant difficulties in language development and reading acquisition. They may require an intervention that targets multiple domains. Interventions that focus primarily on the child’s perceptual and phonological knowledge of intra-word units have been shown to result in as much change in speech accuracy as articulation therapy while having the added benefit of improving the child’s metalinguistic and prereading skills (Rvachew & Brosseau-Lapré, 2012; Hesketh, Adams, Nightingale, & Hall, 2000). When using an alternating goal attack strategy, focused stimulation can be used to successfully treat both speech production and grammatical errors during the same treatment block (Tyler, Lewis, Haskill, & Tolbert, 2003).
When SLPs treat children with SSDs, they often use an eclectic approach, selecting from among the procedures described above in order to address the child’s particular needs and parent’s preferences or to conform to local administrative constraints on clinical practice (Joffe & Pring, 2008). The effectiveness of speech therapy in real world settings is not assured when clinical practice does not conform to the details of research-based interventions and thus clinic-based treatment efficacy research is important. One study demonstrated that eclectic speech therapy is more effective than no treatment when eight sessions of treatment were provided over a 3-month interval (Lancaster, Keusch, Levin, Pring, & Martin, 2010). Another study suggested that varied treatment procedures, including the home program component, are most effective when they are selected to be theoretically coherent (Rvachew & Brosseau-Lapré, 2012). Emerging evidence suggests that different treatment procedures must be matched to the child’s SSD subtype, although confirmation with larger intervention trials is required (Dodd & Bradford, 2000).
3. How much speech therapy is required for a good outcome?
A number of studies suggest that approximately 20 hours of speech therapy, spread over a minimum of 15 weeks, are required before the child’s speech will be noticeably more intelligible (Jacoby, Levin, Lee, Creaghead, & Kummer, 2002; Schooling, 2003). However, half as much treatment may be sufficient if the child receives a structured home program in addition to speech therapy. Several studies have demonstrated that parents can be effective treatment agents when provided with structured and appropriately intensive training in the implementation of the home program (Sommers, 1962; Sommers et al., 1964; Eiserman, Weber, & McCoun, 1992; Eiserman, Weber, & McCoun, 1995). For complex cases, as many as 100 hours of treatment may be required (Campbell, 1999). Inadequate intensity of service is likely one reason that speech therapy services are not always shown to be effective. Therefore, in addition to the effective practices described above, adequate amounts of individual service time appear to be necessary for successful treatment.
Directions for Future Research
New technologies for providing visual feedback have been developed but are as yet untested in randomised control trials.Given the investment required for computer equipment and clinician training, the effectiveness of these new tools should be compared to less costly traditional procedures in carefully controlled studies.
It is known that children with SSD are not all the same; the underlying reason for the speech problem may differ from child to child. There is an urgent need for large-scale studies of interactions between the nature of the child’s speech problem and the kind of therapy that is most effective for different subtypes of SSD.
Large-scale studies of treatment effectiveness in natural clinic environments are also important. Further research that investigates the impact of speech therapy on longer term functional outcomes would be valuable (i.e., speech intelligibility, social-emotional functioning, and academic success). Systematic study of the most efficient means of providing effective speech therapy is also urgently required.
Children with SSD who receive speech therapy make faster progress than those who do not. However, speech therapy is not always effective enough to ensure that children achieve age-appropriate speech before they begin school. If the social and academic problems that are often associated with SSD are to be prevented, clinicians must provide enough service and use the most effective and efficient speech therapy practices.
Research evidence supports the use of approaches that address the child’s phonological system as a whole. Procedures that improve the child’s perceptual, articulatory, and phonological knowledge of misarticulated speech sounds have been shown to be effective. Most children with a speech sound disorder can achieve a good outcome with 20 hours of intervention but some children require as many as 100 hours of speech therapy to achieve intelligible speech.
More research is required to understand which types of speech sound disorders respond best to different speech therapy practices. More research to establish the effectiveness of new technologies is also necessary. Systematic study of the relative effectiveness and efficiency of different service delivery models is required. These studies should follow children long enough to document the effect of the treatment on social-emotional and academic outcomes as well as on short-term improvements in speech accuracy.
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