Speech-generating devices (SGDs), also known as voice output
communication aids, are electronic augmentative and alternative
communication (AAC) systems used to supplement or replace speech or
writing for individuals with severe speech impairments, enabling
them to verbally communicate.[1] SGDs are important for people who
have limited means of interacting verbally, as they allow
individuals to become active participants in communication
interactions. They are particularly helpful for patients suffering
from amyotrophic lateral sclerosis (ALS) but recently have been
used for children with predicted speech deficiencies.
There are several input and display methods for users of varying
abilities to make use of SGDs. Some SGDs have multiple pages of
symbols to accommodate a large number of utterances, and thus only
a portion of the symbols available are visible at any one time,
with the communicator navigating the various pages.
Speech-generating devices can produce electronic voice output by
using digitized recordings of natural speech or through speech
synthesis—which may carry less emotional information but can permit
the user to speak novel messages.
The content, organization, and updating of the vocabulary on an SGD
is influenced by a number of factors, such at the user's needs and
the contexts that the device will be used in.[4] The development of
techniques to improve the available vocabulary and rate of speech
production is an active research area. Vocabulary items should be
of high interest to the user, be frequently applicable, have a
range of meanings, and be pragmatic in functionality.
There are multiple methods of accessing messages on devices:
directly or indirectly, or using specialized access
devices—although the specific access method will depend on the
skills and abilities of the user.[1] SGD output is typically much
slower than speech, although rate enhancement strategies can
increase the user's rate of output, resulting in enhanced
efficiency of communication.
The first known SGD was prototyped in the mid-1970s, and rapid
progress in hardware and software development has meant that SGD
capabilities can now be integrated into devices like smartphones.
Notable users of SGDs include Stephen Hawking, Roger Ebert, Tony
Proudfoot, and Pete Frates (founder of the ALS ice bucket
challenge).
Speech-generating systems may be dedicated devices developed solely
for AAC, or non-dedicated devices such as computers running
additional software to allow them to function as AAC devices
