Page 199 - Handbook of Electronic Assistive Technology

Chapter 7 • Alternative and Augmentative Communication 187

Table 7-1 The Percentage of People within Various Diagnostic Groups who could
Potentially Benefit from AAC
• Alzheimer’s/dementia (23.2%)
• Parkinson’s disease (22.7%)
• Autistic spectrum disorder (18.9%)
• Learning disabilities (13.3%)
• Stroke/cerebrovascular accident (9.9%)
• Cerebral palsy (4.5%)
• Head/brain injury (2.3%)
• Profound and multiple learning disability (1.7%)
• Motor neuron disease (1%)
• Other (2.5%)
Creer et al. (2016).

AAC to support children with autism, Wendt (2017) notes that ‘one single best [speech
generating device] or AAC app for autism does not exist! Learners with autism present
with varying needs and learning profiles and should receive individualised AAC solutions’.
Similarly, a systematic review of the role of AAC for persons with developmental disabili-
ties concluded that ‘it is difficult to form conclusions about the effect of augmented input
on specific diagnostic populations’ because of the heterogeneity of these populations and
the occurrence of comorbid conditions (Allen et al., 2017). Once again, the recommenda-
tions are that AAC systems should be chosen as a result of careful assessment and match-
ing the skills of an individual to the specific features of a device.

Defining and Classifying AAC Systems

AAC systems may support both receptive and expressive communication. The former
refers to systems and strategies which support an individual’s understanding of language
and the latter to supporting communicative output and the transmission of messages to a
communication partner.
Within the field of AAC, there exists some debate about the terminology used to describe
the systems and devices used to support those with expressive communication needs. For
the purposes of this chapter, the authors have chosen to use the terms unaided, low-tech
and high-tech to categorise the different types of AAC discussed (Fig. 7-2). An unaided
system is one that relies on a user’s body to convey messages, such as formalised sign lan-
guages, supported signing systems such as Makaton and Signed English or the use of natu-
ral gesture and facial expression. An unaided system requires no additional components,
although will still require teaching and practice for a person to develop the skills needed to
be an effective user. The other two categories require an additional transmission device or
method. A low-tech system is usually a method such as a communication book or board,
containing written text, graphic symbols, pictograms or photographs. A high-tech sys-
tem is one that requires either a battery or mains power. This category includes dedicated
communication aid devices making use of synthetic or digitally recorded voice output,