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Speech Generating Devices for Communication

Speech Generating Devices are assistive technology electronic devices that allow individuals to communicate through assistive technology. They are also called Voice Output Communication Aids (VOCA). They speak out messages as a user types words or selects pictures/symbols.

Speech-Generating Devices (SGD) are a type of Augmentative and alternative communication (AAC) systems that enable individuals with complex communication needs to express themselves. They help people with speech and language difficulties communicate better. Moreover, SGDs also enable users to gain language and literacy skills.

Speech Generating Devices

Evolution of SGDs

SGD was first prototyped during the 1970s. Since then, advancements in software and hardware has allowed smartphones and tablets to include SGD capabilities. Stephen Hawking is one of the well-known users of SGDs. Other prominent users include Tony Proudfoot, Roger Ebert,  and Pete Frates (ALS Ice Bucket Challenge founder).

Speech generating devices can be dedicated systems developed solely for communication. They can also be computers that run additional software, allowing their serving as AAC systems.

Types of Speech-Generating Devices

There are many types of SGDs and VOCAs which include the following:

Devices that Produce a Single message 
Single-level Devices.

The pictures/ words on the display may be changed, to suit the vocabulary programmed into the device.

Static Display

The display is static and doesn’t change. Typically, one key represents one symbol in these Speech Generating Devices. The communicator can select the keys to construct a message.

Dynamic Display

These are high-tech devices such as a tablet, a computer, or a touch screen device. These SGDs typically contain extensive vocabulary on multiple pages. Users navigate these pages to construct messages which can be single words, phrases/ sentences. They may also be compatible with several switch access systems. 

Text-to-Speech Devices

These devices convert the messages a user has typed to synthesised speech. The keyboard may be a digital interface or a physical keyboard. Much like modern-day phones and tablets, they may also have spell check and word prediction. 

Vocabulary in Speech Generating Devices

All the symbols and messages available to an individual using SGD is called the selection set. Several factors determine the content of the selection set. The user’s motor and cognitive abilities, interests, age, and challenges influence the words in the set. Additionally, the set will typically have words already familiar to the user along with ones that they will ‘grow’ to learn.

Researchers such as Beukelman and Mirenda say that family members, teachers, friends, and caregivers give inputs for the initial content of an Speech Generating Device. It’s best to have a variety of sources inform the words to include in the system. This is because, generally speaking, one individual will not have enough knowledge or experience to come up with all the possible vocal expressions needed in a certain environment.

Avaz AAC Screen

Researchers Musselwhite and St. Louis have suggested that the initial vocabulary set should have words/symbols that are of high interest to a user. The criteria also includes frequently applicable words and those that have a wide range of meanings and pragmatic in functionality.

Maintenance of Content in SGDs

Quick access to core words

Beukelman and Mirenda reiterate the importance of ongoing maintenance of vocabulary in an SGD. This means that one needs to keep adding words to suit the user’s needs. For example, for an AAC user in school, their vocabulary set should include words that allow them to participate in classroom discussions. Moreover, as the user grows older, more age-appropriate words need to be added so that they can converse with their peers.

The AAC users’ Speech Langauge Pathologists, teacher, caregiver, parent, or the user themselves can add words and maintain the content. They may need knowledge of how to program the SGD. Manufactures usually have training programs and manuals that guide them how to customise the SGD according to each individual’s needs. Training of families and caregivers is very important to help the AAC user get the best out of their Speech Generating Devices. 


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