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A Comparison of the Use of Low-Tech and High-Tech Communication Systems for Children with CAS

Published | By
Korey L. Stading M.S., CCC-SLP Munroe-Meyer Institute, RiteCare Clinic University of Nebraska Medical Center and Amy S. Nordness Ph.D, CCC-SLP Madonna Rehabilitation Hospital


Children diagnosed with childhood apraxia of speech (CAS) struggle to communicate basic needs to even those closest to them. In addition to severely unintelligible speech, CAS is often accompanied by language and literacy deficits, academic difficulties, deficits in phonological processing and literacy, and social disadvantages (ASHA, 2007; Lewis, Freebairn, Hansen, Stein, Shriberg, Iyengar, et al., 2006; Overby, Carrell & Bernthal, 2007). Since children with CAS have such restricted sound systems, they cannot build more complex words and sentences, which in turn restricts their expressive language development. Children with CAS who communicated with voice output devices enhanced their expressive language by increasing mean length of utterances (MLU), increased overall language skills, increased number of words, number of different words, and multi-word messages, and increased speech accuracy (Cumley & Swanson, 1999; Miller, Light, & Schlosser, 2006; Stading, Ball, Larson, & Dulany, 2005). Miller and colleagues (2006) also found that supporting communication with a voice output device did not decrease the number of speech attempts.  Research has also shown that children with CAS who use voice output devices were able to repair communication breakdowns, establish topics, have longer social interactions, participate more in academics, reduce non-communicative behaviors, and had people speaking for them less (Culp, 1989; Cumley & Swanson, 1999; Stading, et al., 2005).

Despite the availability and supportive evidence of voice output devices, children with CAS frequently do not use them due to high cost, lack of insurance reimbursement, and parental fear of the child giving up on speech.  Initial research has shown devices increase speech and language development and give the child a way to communicate more effectively with others.  They provide a speech model during each communicative use, which is suspected to increase natural speech, expressive language and communicative effectiveness.  However, no available research has determined the effectiveness of high-tech voice output devices compared to low-tech communication systems in their impact on components of speech and language development.

This study compared the impact of high-tech voice output devices to low-tech communication systems and no-tech communication on accuracy of speech, expressive language, and communication interaction (CI) for children with CAS.



Two children with severe CAS, between the ages of 5-6, participated in this study. Each child used mainly single words in speech productions, and had issues with intelligibility of spontaneous speech with all communication partners. Each child was able to navigate a dynamic display communication device.


We utilized a single subject alternating-treatment design to measure the effects of high-tech, low-tech and no-tech (speech only) communication supports on speech, expressive language, and Communication Interaction for children with CAS. The study occurred over the course of a year. Each child received their own voice output device (i.e., DynaVox V) for the entire year in addition to low-tech communication boards (i.e., screen shots from their DynaVox V). The participants received individual therapy 3 times per week. Two sessions focused on speech sound development, and one session focused on use of the voice output communication device and low-tech communication boards. Half of each session was spent using the DynaVox V and half was spent using the low-tech communication board. The order was alternated each session. Training on use of the communication systems occurred for an average of 21 sessions, until each child passed a performance test with at least 80% accuracy to ensure competency of navigation on the systems.

Data was collected on the percentage of consonants correct (PCC), percentage of vowels correct (PVC), variety of types of words used (e.g., nouns, verbs, article, etc.), Mean Length of Utterance (MLU), and on communication interaction (i.e., adequate, inadequate, and ambiguous responses, initiations, recodes, comments, obliges, no responses, and requests for clarifications) The Communication Interaction measures were based on research by Blank & Franklin (1980). This data was collected at baseline during three different treatment sessions. Treatment data was collected after each child passed their performance test. Data was collected monthly during treatment sessions for six months. Data was collected in each of the three conditions (speech only, high-tech voice output communication device, low-tech communication boards)


The use of a communication system, either low-tech or high-tech, did have a positive impact on many of the language and communication interaction measures. There was no change in the Percent of Consonants Correct or Percent of Vowels Correct across conditions, indicating that the use of a communication system did not impact the child’s articulation of words. However, it was not expected that a communication system would improve the actual accuracy of speech productions in a positive or negative way. There was an increase in the Mean Length of Utterance when both low-tech communication boards and high-tech voice output communication devices were use, which means that the children were combining more words to make longer phrases or sentences when they used a communication system as compared to their speech alone. There was an increase in the use of adjectives when both communication systems were used as well, but this impact was not seen for other grammatical components of language. There was a decrease in the use of yes/no responses when high-tech communication devices were used. This means they were not giving yes/no answers as often, but were providing more complex answers.

When Communication Interaction was measured, there were many benefits seen in the use of communication systems. There were a decrease in responses, and an increase in initiations for children using both low-tech and high-tech communication systems. This means they were not just responding to questions, but they were initiating communication more often and helping to direct the conversation. This resulted in an increase in comments, where the child initiates sharing information on a topic. There was also an increase in recodes, or clarification or expansion of a communication attempt, when either a low-tech or high-tech communication system was used. There was a slight benefit in the use of low-tech communication boards on the increase of obliges, which is asking a question or making a statement that requires a response from your communication partner. There were more adequate, or accurate, responses when high-tech voice output communication devices were used, as compared to speech only and low-tech communication boards. There was also a decrease in no responses, which is ignoring or not responding to a question asked, in all three conditions as compared to baseline data. This means that the children were attempting to communicate more overall. See the table below for a summary of the results.

No Change Speech Only Low-Tech High-Tech
PVC Decrease in Negatives and Affirmatives
All other grammatical parts of speech Increase in Adjective use
Request for Clarification Decrease in Responses Decrease in Responses
Increase in Initiations Increase in Initiations
Increase in Comments Increase in Comments
Increase in Recodes Increase in Recodes
Increase in Obliges
Increase in Adequate Responses
Decrease in No Responses Decrease in No Responses Decrease in No Responses


Both low-tech communication boards and high-tech voice output communication devices showed a significant benefit over the use of speech alone in communication. The biggest changes were seen in Communication Interaction measures. They were able to initiate, comment on topics, ask questions, and clarify their messages more. They also used longer phrases and sentences when communication systems were used and increased their use of adjectives. The use of these systems did not have a negative impact on their speech productions either.

There were benefits of both low-tech and high-tech communication systems, but high-tech voice output devices had a slight advantage, as they lead to a decrease in reliance on yes/no answers to questions and an increase in accurate responses in this study. This advantage was slight, and much less than was hypothesized. This may be because the low-tech communication boards used in the study consisted of screen shots from their DynaVox pages. This was done to make the two systems as comparable as possible, but it is not how low-tech communication boards are typically set up. These were full communication pages, not anything like a Picture Exchange Communication System (PECS) notebook. These low-tech systems contained vocabulary focused on building sentences, commenting, giving an opinion, and asking questions (core word pages, quickfires/chat, and my phrases). This type of vocabulary is important for growth in many of the measured areas, and it should be included in all forms of communication systems for children with CAS, low-tech or high-tech. Traditional PECS systems typically allow for some combining of words (I want ___, or colors + objects), but they focus on requesting items. They do not typically support commenting, asking questions, or stating an opinion. These types of communications are typical for children, and inclusion of this vocabulary is critical to see changes in communication interaction as described above. Page editing software is typically free to download for most dynamic display voice output communication devices. This can be used as a guide to identify vocabulary that is important to include when setting up communication systems for children with CAS.


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