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Katya Hill, Ph.D., CCC-SLP
Edinboro University of Pennsylvania

Robin Hurd
Parent of twins who rely on AAC

Children are a precious resource for the future. Children with complex communication needs (CCN) are precious resources for the future that may frequently go unnoticed because of limited communication competence. Since the essential goal of AAC (augmentative and alternative communication) is the most effective communication possible for the individual being served, then children with CCN should qualify for being provided services to achieve this goal. Achieving the goal requires following a principled, systematic approach to intervention. Like most health care professionals, AAC professionals are expected to follow the principles of evidence-based practice (EBP) to achieve the best results. For many AAC professionals, the client is a child with CCN.

EBP starts with practitioners holding the interests of the child with CCN paramount. The basic principles of EBP require practitioners to seek field evidence after asking the best questions given the information (data) collected on the child and the problem (Gibbs, 2003). For practitioners applying the principles of EBP, the conscientious collection of information to characterize and measure the problem is essential to formulating the best questions before looking for evidence about possible interventions. After appraising the evidence and implementing the intervention, the monitoring of outcomes is expected.

Automated performance measurement is providing methods and tools that allow for the reporting of quantitative data based on units of measurement to support evidence-based practice. A language activity monitor (LAM) was developed originally as a device to be added to existing AAC assistive technology systems (Hill & Romich, 2001). Several modern high performance AAC systems now have the data logging function as a built-in standard feature. U-LAM (Universal LAM) is software that allows practitioners to collect logfiles with most AAC systems (Hill & Romich, 2003). PeRT (Performance Report Tool) is software that provides a fast and convenient approach to generating an AAC Performance Report (Hill & Romich, 2003). U-LAM and PeRT are downloadable programs from the AAC Institute (http://www.aacinstitute.org).

Performance measurement provides a systematic method of documenting the progress toward the acquisition of language competency using AAC strategies. Few studies exist documenting the AAC system activity and performance of children with CCN. This paper summarizes case study results of monitoring the intervention process of children being introduced to high technology voice output AAC systems. AAC performance measurement tools were used to collect, analyze, and report communication competence during intervention.

Intervention was designed to build communicative competence using an AAC system and multi-modal methods of communication. Intervention strategies emphasized a language-based approach that relied on domains of communication competence to target skills (Light, 1989; Light & Binger, 2001; Hill, 2001). Performance and outcomes measurement tools and methods were used to monitor change during AAC intervention. After baseline data were obtained intervention was initiated. Data were collected during therapy sessions using the LAM, observational recording of responses, and occasional videotaping. LAM logfiles were uploaded into the computer for transcription, analysis, and reporting. The language samples collected during 45 to 90 minutes of child-centered therapy activities were analyzed using PeRT and the Systematic Analysis of Language Transcripts (SALT). Random sampling of 10% of the transcripts was performed to confirm inter-rater reliability of the transcription process.

Case study data were collected for five children using AAC voice output systems. These children ranged in age from 3.5 to 13.0 years old and consisted of three males and two females. Medical diagnoses included three children with severe spastic quadriplegia cerebral palsy, one child with mild cerebral palsy and verbal apraxia, and one child with developmental disabilities. All children were using synthesized speech voice output devices. The five children used AAC systems that supported the three language representation methods of single meaning pictures, alphabet-based methods, and semantic compaction. Two children had a dynamic display device, one child had a 128 location static keyboard device, and two children had a hybrid device with a 128 static keyboard and dynamic display.

For the purpose of this paper, four domains of communication competence with the corresponding summary measures based on LAM data were selected to monitor change.
1. Language Representation Skills
2. Linguistic Skills/Form
3. Linguistic Skills/Content
4. Strategic/Construction Skills

Specific summary measures include the frequency of use of the language representation methods, the mean length of utterance, the frequency of use of core versus extended vocabulary, and the frequency of use of SNUG (spontaneous novel utterance generation) versus pre-stored messages.

Language Representation Methods

The results from these children demonstrate the feasibility and reliability of reporting performance data on children who rely on AAC on the frequency of use for how language is generated on AAC systems. The children spontaneously used semantic compaction to select an overwhelming majority of single words and word phrases ranging from 50% to 85%. For these children, the use of single meaning pictures was significantly more frequent than reported for the adult population (Hill 2001) using similar language application programs.

Linguistic Skills/Form

The results from these children show increases in mean length of utterance (MLU-w, MLU-m) using AAC systems following intervention. Results show gradual increases in the range of utterance lengths from 1-word utterances to MLUs of 3.5 words and higher. Utterances have been compared with Brown's Stages (1973) and show the variety of syntactic diversity possible for children who rely on AAC language application programs that support access to core vocabulary and morphemes.

Linguistic Skills/Content

Marvin, Beukelman, and Bilyeu (1994) was used as a foundation for the most frequently used words for children. One of the primary objectives of therapy for children who rely on AAC should be to ensure a natural balance between use of core and extended vocabulary. Results from the case studies show the feasibility of reporting the frequency of use of core and extended vocabulary. Data tend to indicate a shift toward increased use of core vocabulary as children have more experience with the device. Core vocabulary was used 30% of time during introductory sessions, but increased to over 70% use during later sessions.

Strategic Construction Skills

From the initiation of therapy, the emphasis was placed on modeling the use of single words to generate spontaneous novel utterances. Results show the use of spontaneous utterances over 90% of the time during language-based therapy sessions. However, an increase in the use of pre-stored utterances occurred during activity-based sessions that are more reflective of typical classroom settings.


These case studies demonstrate the feasibility of using LAM and PeRT to support the AAC intervention process. The data document performance measures for children who rely on AAC. Parental involvement in the intervention process facilitated the data collection and reporting processes. These case studies contribute to a growing pool of evidence regarding AAC performance monitoring and outcomes measurement.


Brown, R. (1973). A first language, the early stages. Cambridge, MA: Harvard University Press.

Hill, K.J. (2001). The development of a model for automated performance measurement and the establishment of performance indices for augmented communicators under two sampling conditions. (unpublished dissertation). Pittsburgh, Pennsylvania: University of Pittsburgh.

Hill, K.J. and Romich, B.A. (2001). A summary measure clinical report for characterizing AAC performance. In Proceedings of the RESNA Conference, Arlington, VA: RESNA Press. 55-57.

Light, J. (1989). Toward a definition of communicative competence for individuals using augmentative and alternative communication systems. AAC Augmentative and Alternative Communication, 5, 137-144.

Light, J., & Binger, C. (1998). Bulding communicative competence with individuals who use augmenative and alternative communication. Baltimore, MD: Paul H. Brookes Publishing Co.

Marvin, C.A., Beukelman, D.R., & Bilyeu D. (1994). Vocabulary-use patterns in preschool children: Effects of context and time sampling. AAC Augmentative and Alternative Communication, 10, 224-236.

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