A doctoral student and her professors in electronics and electrical engineering at Loughborough University in the United Kingdom have published an article on Alternative and Augmentative Communication [AAC] approaches incorporating advanced technologies, focusing in particular on the current state of input technologies designed for persons with speech disabilities who use a high-tech AAC device to communicate. The goals of the article are: (1) to provide a comprehensive survey of relevant and currently available signal-detecting technologies; (2) to characterize their operational principles and user demands; and (3) to indicate their relative advantages, disadvantages, and potentials for future improvements.

The authors work within the existing Human Activity Assistive Technology [HAAT] model, which in turn draws upon prior work by Chapanis and others of human factors in systems engineering, generally. A key constituent in the HAAT model is the interface between the user and the assistive technology, and here the authors of the current study focus in particular on the options for obtaining input through signal detection of users’ volitional, intentional control acts. They identify 5 interface approaches supporting such signal transmission: [i] imaging methods (used for eyegaze- and headpointing-detection), [ii] electromechanical methods (used with keyboards and switches), [iii] areal touch-activated approaches (e.g., touchscreens), [iv] breath-activated methods (used in microphones, low-pressure sensors), and [v] brain-computer interface [BCI] methods (involving surface electrodes or implants).

For each of these five options, the authors provide an analysis and discussion of operational features, formulated with some rigor. For example, in the section on eyegaze technologies, the authors provide mathematical formulae for calculating pixel accuracy around targets, and for characterizing operational demands precisely, given knowledge of user distance from screen and target size. They summarize their findings regarding all these input technologies in a table that presents, for each approach, columns that list the signal sources, the various modes of detecting such signals, typical hardware requirements for capture and processing, strengths, limitations, and needed improvements.

Overall, the authors note that special purpose-developed technologies are typically complex, costly, and high-maintenance. They identify new apps as a possible approach to introduce more affordable options. Many persons with aphasia have adequate motor, sensory, and cognitive skills to use such apps.


For further reading:   Y. Elsahar, S. Hu, K. Bouazza-Amrouf et al., 2019,  Augmentative and alternative communication (AAC) Advances: A review of con-figurations for individuals with a speech disability.  Sensors, 19(8), 1911, 1-24. https://doi.org/10.3390/s19081911

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