![Stephen Hawking 050506](https://upload.wikimedia.org/wikipedia/commons/3/31/Stephen_Hawking_050506.jpg)
Speech-generating devices (SGDs), also known as voice output communication aids, are electronic
augmentative and alternative communication
Augmentative and alternative communication (AAC) encompasses the communication methods used to supplement or replace speech or writing for those with impairments in the production or comprehension of spoken or written language. AAC is used by t ...
(AAC) systems used to supplement or replace speech or writing for individuals with severe
speech impairment
Speech disorders or speech impairments are a type of communication disorder in which normal speech is disrupted. This can mean stuttering, lisps, etc. Someone who is unable to speak due to a speech disorder is considered mute. Speech skills are ...
s, enabling them to verbally communicate.
[ Aetna Inc. (2010)] 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 with
amyotrophic lateral sclerosis
Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most comm ...
(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
Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products. A text-to-speech (TTS) system converts normal languag ...
—which may carry less emotional information but can permit the user to speak novel messages.
[ Glennen & Decoste pp. 88–90]
The content, organization, and updating of the vocabulary on an SGD is influenced by a number of factors, such as the user's needs and the contexts that the device will be used in.
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.
[ 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
Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work.
At the lowest programming level, executable code consists ...
development has meant that SGD capabilities can now be integrated into devices like smartphones
A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, which ...
. Notable users of SGDs include Stephen Hawking, Roger Ebert
Roger Joseph Ebert (; June 18, 1942 – April 4, 2013) was an American film critic, film historian, journalist, screenwriter, and author. He was a film critic for the ''Chicago Sun-Times'' from 1967 until his death in 2013. In 1975, Ebert beca ...
, Tony Proudfoot
John A. "Tony" Proudfoot (10 September 1949 – 30 December 2010) was an All-Star defensive back in the Canadian Football League, teacher, coach, broadcaster and journalist.
He was a Grey Cup champion twice as a player, and twice as special co ...
, and Pete Frates
The Ice Bucket Challenge, sometimes called the ALS Ice Bucket Challenge, is an activity involving the pouring of a bucket of ice water over a person's head, either by another person or self-administered, to promote awareness of the disease amy ...
(founder of the ALS Ice Bucket Challenge
The Ice Bucket Challenge, sometimes called the ALS Ice Bucket Challenge, is an activity involving the pouring of a bucket of ice water over a person's head, either by another person or self-administered, to promote awareness of the disease amyo ...
).
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.[ Glennen, pp. 62–63.][ Jans & Clark (1998), pp. 37–38.]
History
SGDs have their roots in early electronic communication aids. The first such aid was a sip-and-puff
Sip-and-puff or sip 'n' puff (SNP) is assistive technology used to send signals to a device using air pressure by "sipping" (inhaling) or "puffing" (exhaling) on a straw, tube or "wand." It is primarily used by people who do not have the use o ...
typewriter controller named the patient-operated selector mechanism (POSSUM) prototyped by Reg Maling in the United Kingdom in 1960.[ Vanderheide (2002)][ Zangari (1994)] POSSUM scanned through a set of symbols on an illuminated display. Researchers at Delft University
Delft University of Technology ( nl, Technische Universiteit Delft), also known as TU Delft, is the oldest and largest Dutch public technical university, located in Delft, Netherlands. As of 2022 it is ranked by QS World University Rankings among ...
in the Netherlands created the lightspot operated typewriter (LOT) in 1970, which made use of small movements of the head to point a small spot of light at a matrix of characters, each equipped with a photoelectric cell. Although it was commercially unsuccessful, the LOT was well received by its users.[ Stassen et al., p. 127]
In 1966, Barry Romich, a freshman engineering student at Case Western Reserve University, and Ed Prentke, an engineer at Highland View Hospital in Cleveland, Ohio formed a partnership, creating the Prentke Romich Company.[PRC History](_blank)
/ref> In 1969, the company produced its first communication device, a typing system based on a discarded Teletype machine.
During the 1970s and early 1980s, several other companies began to emerge that have since become prominent manufacturers of SGDs. Toby Churchill
Toby Churchill DEng FRSA (born 29 June 1947) is a disabled British entrepreneur. He founded a company manufacturing communication aids for people who cannot speak.
Biography
He is the eldest son of Oliver Churchill and Ruth (née Briggs). He was ...
founded Toby Churchill Ltd in 1973, after losing his speech following encephalitis.[ Toby Churchill (About Us)] In the US, Dynavox
Tobii Dynavox is a SE-based developer, manufacturer, and distributor of speech generating devices headquartered in Danderyd, Sweden with offices in Pittsburgh, Norway, Germany, France, the UK, China, Japan, South Korea, and Taiwan.
The company ...
(then known as Sentient Systems Technology) grew out of a student project at Carnegie-Mellon University
Carnegie Mellon University (CMU) is a private research university in Pittsburgh, Pennsylvania. One of its predecessors was established in 1900 by Andrew Carnegie as the Carnegie Technical Schools; it became the Carnegie Institute of Technology ...
, created in 1982 to help a young woman with cerebral palsy
Cerebral palsy (CP) is a group of movement disorders that appear in early childhood. Signs and symptoms vary among people and over time, but include poor coordination, stiff muscles, weak muscles, and tremors. There may be problems with sensa ...
to communicate.
Beginning in the 1980s, improvements in technology led to a greatly increased number, variety, and performance of commercially available communication devices, and a reduction in their size and price. Alternative methods of access such as Target Scanning (also known as eye pointing) calibrate the movement of a user's eyes to direct an SGD to produce the desired speech phase. Scanning, in which alternatives are presented to the user sequentially, became available on communication devices.[ Hourcade (2004).] Speech output possibilities included both digitized and synthesized speech.
Rapid progress in hardware and software
Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work.
At the lowest programming level, executable code consists ...
development continued, including projects funded by the European Community
The European Economic Community (EEC) was a regional organization created by the Treaty of Rome of 1957,Today the largely rewritten treaty continues in force as the ''Treaty on the functioning of the European Union'', as renamed by the Lisbo ...
. The first commercially available dynamic screen speech-generating devices were developed in the 1990s. Software programs were developed that allowed the computer-based production of communication boards. High-tech devices have continued to become smaller and lighter, while increasing accessibility and capability; communication devices can be accessed using eye-tracking systems, perform as a computer for word-processing and Internet use, and as an environmental control device
An environmental control device is a form of electronic assistive technology which enables people with significant disabilities to independently access equipment in their environment e.g. home or hospital.
An environmental control controller is t ...
for independent access to other equipment such as TV, radio and telephones.
Stephen Hawking came to be associated with the unique voice of his particular synthesis equipment. Hawking was unable to speak due to a combination of disabilities caused by ALS
Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most com ...
, and an emergency tracheotomy
Tracheotomy (, ), or tracheostomy, is a surgical airway management procedure which consists of making an incision (cut) on the anterior aspect (front) of the neck and opening a direct airway through an incision in the trachea (windpipe). The ...
. In the past 20 or so years SGD have gained popularity amongst young children with speech deficiencies, such as autism, Down syndrome, and predicted brain damage due to surgery.
Starting in the early 2000s, specialists saw the benefit of using SGDs not only for adults but for children, as well. Neuro-linguists found that SGDs were just as effective in helping children who were at risk for temporary language deficits after undergoing brain surgery as it is for patients with ALS. In particular, digitized SGDs have been used as communication aids for pediatric patients during the recovery process.
Access methods
There are many methods of accessing messages on devices: directly, indirectly, and with specialized access devices. Direct access methods involve physical contact with the system, by using a keyboard or a touch screen. Users accessing SGDs indirectly and through specialized devices must manipulate an object in order to access the system, such as maneuvering a joystick
A joystick, sometimes called a flight stick, is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. A joystick, also known as the control column, is the principal cont ...
, head mouse, optical head pointer, light pointer, infrared pointer, or switch access scanner.[
The specific access method will depend on the skills and abilities of the user. With direct selection a body part, pointer, adapted ]mouse
A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
, joystick
A joystick, sometimes called a flight stick, is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. A joystick, also known as the control column, is the principal cont ...
, or eye tracking could be used, whereas switch access scanning is often used for indirect selection.[ Unlike direct selection (e.g., typing on a keyboard, touching a screen), users of Target Scanning can only make selections when the scanning indicator (or cursor) of the electronic device is on the desired choice.] Those who are unable to point typically calibrate their eyes to use eye gaze as a way to point and blocking as a way to select desired words and phrases. The speed and pattern of scanning, as well as the way items are selected, are individualized to the physical, visual and cognitive capabilities of the user.[ Beukelman & Mirenda, pp. 97–101]
Message construction
Augmentative and alternative communication is typically much slower than speech,[ University of Washington (2009)] with users generally producing 8–10 words per minute.[ Higginbotham et al (2007)] Rate enhancement strategies can increase the user's rate of output to around 12–15 words per minute, and as a result enhance the efficiency of communication.
In any given SGD there may be a large number of vocal expressions that facilitate efficient and effective communication, including greetings, expressing desires, and asking questions.[ Beukelman & Mirenda] Some SGDs have multiple pages of symbols
A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different conc ...
to accommodate a large number of vocal expressions, and thus only a portion of the symbols available are visible at any one time, with the communicator navigating the various pages.[ Hochstein et al (2004)] Speech-generating devices generally display a set of selections either using a dynamically changing screen, or a fixed display.
There are two main options for increasing the rate of communication for an SGD: encoding and prediction.
Encoding permits a user to produce a word, sentence or phrase using only one or two activations of their SGD. Iconic encoding strategies such as Semantic compaction combine sequences of icons (picture symbols) to produce words or phrases.[ Venkatagiri (1995)] In numeric, alpha-numeric, and letter encoding (also known as Abbreviation-Expansion), words and sentences are coded as sequences of letters and numbers. For example, typing "HH" or "G1" (for Greeting 1) may retrieve "Hello, how are you?".
Prediction is a rate enhancement strategy in which the SGD attempts to reduce the number of keystrokes used by predicting the word or phrase being written by the user. The user can then select the correct prediction without needing to write the entire word. Word prediction
Autocomplete, or word completion, is a feature in which an application predicts the rest of a word a user is typing. In Android and iOS smartphones, this is called predictive text. In graphical user interfaces, users can typically press the tab ...
software may determine the choices to be offered based on their frequency in language, association with other words, past choices of the user, or grammatical suitability.[ Augmentative Communication, Incorporated] However, users have been shown to produce more words per minute (using a scanning interface) with a static keyboard layout than with a predictive grid layout, suggesting that the cognitive overhead of reviewing a new arrangement cancels out the benefits of the predictive layout when using a scanning interface.[ Johansen et al (2003)]
Another approach to rate-enhancement is Dasher,[ Ward et al (2000)] which uses language models and arithmetic coding
Arithmetic coding (AC) is a form of entropy encoding used in lossless data compression. Normally, a string of characters is represented using a fixed number of bits per character, as in the ASCII code. When a string is converted to arithmetic ...
to present alternative letter targets on the screen with size relative to their likelihood given the history.[ Roark et al (2010)]
The rate of words produced can depend greatly on the conceptual level of the system: the TALK system, which allows users to choose between large numbers of sentence-level utterances, demonstrated output rates in excess of 60 wpm.[ Todman (2000)]
Fixed and dynamic display devices
Fixed display devices
Fixed display devices refer to those in which the symbols and items are "fixed" in a particular format; some sources refer to these as "static" displays.[ Hochstein et al (2003)] Such display devices have a simpler learning curve than some other devices.
Fixed display devices replicate the typical arrangement of low-tech AAC devices (low-tech is defined as those devices that do not need batteries, electricity or electronics), like communication boards. They share some of disadvantages; for example they are typically restricted to a limited number of symbols and hence messages.[ Beukelman & Mirenda p. 84-85] It is important to note that with technological advances made in the twenty-first century, fixed-display SGDs are not commonly used anymore.
Dynamic display devices
Dynamic displays devices are usually also touchscreen
A touchscreen or touch screen is the assembly of both an input ('touch panel') and output ('display') device. The touch panel is normally layered on the top of an electronic visual display of an information processing system. The display is often ...
devices. They typically generate electronically produced visual symbols that, when pressed, change the set of selections that is displayed. The user can change the symbols available using page links to navigate to appropriate pages of vocabulary and messages.
The "home" page of a dynamic display device may show symbols related to many different contexts or conversational topics. Pressing any one of these symbols may open a different screen with messages related to that topic. For example, when watching a volleyball game, a user may press the "sport" symbol to open a page with messages relating to sport, then press the symbol showing a scoreboard to utter the phrase "What's the score?".
Advantages of dynamic display devices include the availability of a much larger vocabulary, and the ability to see the sentence under construction A further advantage of dynamic display devices is that the underlying operating system is capable of providing options for multiple communication channels, including cell phone
A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whil ...
, text messaging
Text messaging, or texting, is the act of composing and sending electronic messages, typically consisting of alphabetic and numeric characters, between two or more users of mobile devices, desktops/laptops, or another type of compatible compute ...
and e-mail. Work by Linköping University
Linköping University (, LiU) is a public research university based in Linköping, Sweden. Originally established in 1969, it was granted full university status in 1975 and is one of Sweden's largest academic institutions. The university has fou ...
has shown that such email writing practices allowed children who were SGD users to develop new social skills and increase their social participation.
Talking Keyboards
Low cost systems can also include a keyboard and audio speaker combination without a dynamic display or visual screen. This type of keyboard sends typed text direct to an audio speaker. It can permit any phrase to be spoken without the need for a visual screen that is not always required. One simple benefit is that a talking keyboard, when used with a standard telephone or speakerphone can enable a voice impaired individual have 2 way conversation over a telephone.
Output
The output of a SGD may be digitized and/or synthesized: digitized systems play directly recorded words or phrases while synthesized speech
Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products. A text-to-speech (TTS) system converts normal languag ...
uses text-to-speech software that can carry less emotional information but permits the user to speak novel messages by typing new words.[ Schlosser, Blischak & Koul (2003)] Today, individuals use a combination of recorded messages and text-to-speech techniques on their SGDs.[ Beukelman & Mirenda p. 105-106] However, some devices are limited to only one type of output.
Digitized speech
Words, phrases or entire messages can be digitised and stored onto the device for playback to be activated by the user.[ This process is formally known as Voice Banking. Advantages of recorded speech include that it (a) provides natural prosody and speech naturalness for the listener][ (e.g., person of the same age and gender as the AAC user can be selected to record the messages),][ and (b) it provides for additional sounds that may be important for the user such as laughing or whistling. Moreover, Digitized SGDs is that they provide a degree of normalcy both for the patient and for their families when they lose their ability to speak on their own.
A major disadvantage of using only recorded speech is that users are unable to produce novel messages; they are limited to the messages pre-recorded into the device.][ Depending on the device, there may be a limit to the length of the recordings.][ Radomski et al (2007)]
Synthesized speech
SGDs that use synthesized speech apply the phonetic
Phonetics is a branch of linguistics that studies how humans produce and perceive sounds, or in the case of sign languages, the equivalent aspects of sign. Linguists who specialize in studying the physical properties of speech are phoneticians. ...
rules of the language to translate the user's message into voice output (speech synthesis
Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products. A text-to-speech (TTS) system converts normal languag ...
).[ Users have the freedom to create novel words and messages and are not limited to those that have been pre-recorded on their device by others.][
Smartphones and computers have increased the use of synthesized speech devices through the creation of apps that allow the user to select from a list of phrases or messages to be spoken in the voice and language that the user has chosen. Apps such as SpeakIt! or Assistive Express for iPhone provide a cheap way to use a speech-generating device without having to visit a doctor's office or learn to use specialized machinery.
Synthesized SGDs may allow multiple methods of message creation that can be used individually or in combination: messages can be created from letters, words, phrases, sentences, pictures, or symbols.][ With synthesized speech there is virtually unlimited storage capacity for messages with few demands on memory space.][
Synthesized speech engines are available in many languages,][ and the engine's parameters, such as speech rate, pitch range, gender, stress patterns, pauses, and pronunciation exceptions can be manipulated by the user.][
]
Selection set and vocabulary
The selection set of a SGD is the set of all messages, symbols and codes that are available to a person using that device.[ Beukelman & Mirenda p. 83] The content, organisation, and updating of this selection set are areas of active research and are influenced by a number of factors, including the user's ability, interests and age.[ Beukelman & Mirenda, Chapter 2] The selection set for an AAC system may include words that the user does not know yet – they are included for the user to "grow into". The content installed on any given SGD may include a large number of preset pages provided by the manufacturer, with a number of additional pages produced by the user or the user's care team depending on the user's needs and the contexts that the device will be used in.
Initial content selection
Researchers Beukelman and Mirenda list a number of possible sources (such as family members, friends, teachers, and care staff) for the selection of initial content for a SGD. A range of sources is required because, in general, one individual would not have the knowledge and experience to generate all the vocal expressions needed in any given environment. For example, parents and therapists might not think to add slang terms, such as " innit".[@article]
Previous work has analyzed both vocabulary use of typically developing speakers and word use of AAC users to generate content for new AAC devices. Such processes work well for generating a core set of utterances or vocal expressions but are less effective in situations where a particular vocabulary is needed (for example, terms related directly to a user's interest in horse riding). The term "fringe vocabulary" refers to vocabulary that is specific or unique to the individual's personal interests or needs. A typical technique to develop fringe vocabulary for a device is to conduct interviews with multiple "informants": siblings, parents, teachers, co-workers and other involved persons.
Other researchers, such as Musselwhite and St. Louis suggest that initial vocabulary items should be of high interest to the user, be frequently applicable, have a range of meanings and be pragmatic in functionality.[ Musselwhite & Louis] These criteria have been widely used in the AAC field as an ecological check of SGD content.
Automatic content maintenance
Beukelman and Mirenda emphasize that vocabulary selection also involves ongoing vocabulary maintenance; however, a difficulty in AAC is that users or their carers must program in any new utterances manually (e.g. names of new friends or personal stories) and there are no existing commercial solutions for automatically adding content. A number of research approaches have attempted to overcome this difficulty, these range from "inferred input", such as generating content based on a log of conversation with a user's friends and family, to data mined from the Internet to find language materials, such as the Webcrawler Project.[ Luo et al (2007)] Moreover, by making use of Lifelog
A lifelog is a personal record of one's daily life in a varying amount of detail, for a variety of purposes. The record contains a comprehensive dataset of a human's activities. The data could be used to increase knowledge about how people liv ...
ging based approaches, a device's content can be changed based on events that occur to a user during their day.[ Reddington & Tintarev (2011)][ Black et al (2010)] By accessing more of a user's data, more high-quality messages can be generated at a risk of exposing sensitive user data. For example, by making use of global positioning systems
The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sys ...
, a device's content can be changed based on geographical location.[ Dominowska et al]
Ethical concerns
Many recently developed SGDs include performance measurement and analysis tools to help monitor the content used by an individual. This raises concerns about privacy
Privacy (, ) is the ability of an individual or group to seclude themselves or information about themselves, and thereby express themselves selectively.
The domain of privacy partially overlaps with security, which can include the concepts of a ...
, and some argue that the device user should be involved in the decision to monitor use in this way. Similar concerns have been raised regarding the proposals for devices with automatic content generation, and privacy is increasingly a factor in design of SGDs. As AAC devices are designed to be used in all areas of a user's life, there are sensitive legal, social, and technical issues centred on a wide family of personal data management problems that can be found in contexts of AAC use. For example, SGDs may have to be designed so that they support the user's right to delete logs of conversations or content that has been added automatically.[ Reddington & Coles-Kemp (2011)]
Challenges
Programming of Dynamic Speech Generating devices is usually done by augmentative communication specialists. Specialists are required to cater to the needs of the patients because the patients usually choose what kinds of words/ phrases they want. For example, patients use different phrases based on their age, disability, interests, etc. Therefore, content organization is extremely time-consuming. Additionally, SGDs are rarely covered by health insurance companies. As a result, resources are very limited with regards to both funding and staffing. Dr. John Costello of Boston Children's Hospital has been the driving force soliciting donations to keep these program running and well-staffed both within his hospital and in hospitals across the country.
See also
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{{DEFAULTSORT:Speech Generating Device
Device
Applications of artificial intelligence
Computational linguistics
Speech and language pathology
Occupational therapy
Augmentative and alternative communication