CHAPTER 2

       Communication Systems for Non-Speaking and Hearing-Impaired People

      The development of a voice-operated typewriter for non-speaking, physically disabled people described in Chapter 1 led to the development of the Talking Brooch. This was one of the first truly portable communication aid for non-speaking people. Demonstrating this to a chance visitor to the Department introduced the challenge of providing a communication aid for a profoundly deaf Member of Parliament and led to the development of a system based on the automatic transcription of machine shorthand.

2.1 A VOICE-OPERATED TYPEWRITER FOR PHYSICALLY DISABLED PEOPLE

      In my readings related to speech recognition research, I had come across a paper that was trying to automatically recognise hand-sent Morse Code. This had not been particularly successful as the timing of hand-sent Morse Code is not accurate. Fast operators can send Morse that can be understood by a human being, but differences in the lengths of the dots and dashes and the spaces within and between characters defeated automatic recognition methods.

      It seemed to me, however, that, if speed was not the overarching objective, an operator could be trained to send Morse Code which could be automatically decoded. Also, the system would provide excellent feedback from errors as, if an “i” (dot-dot), was recognised as an “m” (dash-dash), the operator would know that s/he had to reduce the length of the dots. Thus, spoken Morse code was a possible way in which people who were paralysed from the neck down could type. I simulated VOTEM (Voice Operated Typewriter Employing Morse-code) on the PDP 8 to prove that this was possible and subsequently designed and built an electronic version [Newell and Nabavi, 1969, Newell, A., 1970].

      Clearly, disabled people would have preferred to talk to a typewriter—as some 30-odd years later they would be able to do—but it was not possible at the time. VOTEM was an example of reducing the requirements to match what was possible. Clearly, spoken Morse code was not a viable input method for someone who could use a typewriter keyboard, but was a candidate for someone who could not. This situation is still the case: speech recognition is only really viable in situations where it is not possible or inconvenient to use a keyboard.

      VOTEM—the Voice Operated Typewriter Employing Morse Code sparked my interest in developing technology to assist people with disabilities. It also introduced me to technologically assisted human-human communication. The knowledge and background I had gained in my research into Automatic Speech Recognition showed me that speech communication is very much more than the words which are spoken. Human communication is the very basis of our humanity and is a very complex and subtle process. Our communication with other human beings is not just a set of messages that we relay to other people: it is, in a very real way, our personality. If we are to develop artificial means to replace speech, we must be as concerned about the form of the communication as the efficiency of it as a message carrier.

      I thus embarked on background reading in the area of what was to become known as Augmentative and Alternative Communication (AAC)—technology to support people with impaired speech and language. I also became familiar with a range of (relatively unrelated) research topics that would prove to be very useful in my future research.

      At this time, Possum Controls was one of the leading developers of systems for severely paralyzed people, these were based essentially on scanning a matrix by sucking and blowing down a tube. Figure 2.1 shows an early version of such a system. This technology had been developed by Reg Mailing, who was a “visitor” at Stoke Manderville Hospital. He observed patients using a whistle to communicate with people. At that time even simple electronics was too expensive for this application, but he realized that the Strowger equipment (a two-dimensional mechanical selector mechanism used in telephone exchanges at time) was inexpensive, and could be modified to provide a scanning matrix which could control domestic equipment or an electric typewriter via a pneumatic tube. He formed the POSSUM Company [Mailing and Clarkson, 1963, Mailing, R., 1968], which in the early 21st Century is still marketing communication aids for disabled people.

      By the early 1970s, a number of similar systems had begun to appear [Copeland, K., 1974, Foulds et al., 1975, Ridgeway and Mears, 1985, Vanderheiden, G., 2002]. Some examples of these are shown in Figure 2.2. There were no portable systems, and they all required the disabled person and the conversational partner to look at a remote display or printout. This meant that eye contact, and the ability to notice facial expression, which I believe is very important in face-to-face communication, was not possible. In addition, I thought that an AAC system should be instantly available—so that users did not feel that they had to wait for something important to say, before switching their system on, and that, like speech, it should provide a transitory communication—not a “permanent” written one. An example of the dangers of a printed output was related to me by Arlene Kraat. A non-speaking patient had printed out the message “you did not brush my hair properly” to a nurse, but, instead of this being interpreted as a relatively unimportant comment, it was taken as a formal complaint. This example highlights the difference between the impact of spoken and written messages, which also became a concern in our research into television sub-titling.

      Figure 2.1: An early Possum system.

2.2 THE TALKING BROOCH—A COMMUNICATION AID FOR NON-SPEAKING PEOPLE

      A challenge for AAC systems was to create a portable device that was mounted near to the face. Conventional displays were not appropriate as visual displays at that time were heavy, large, and expensive. My “eureka” moment occurred whilst I was travelling through King’s Cross station where there was a rolling newscaster display, and I remembered Taenzer’s [1970] work aimed at improving the “Opticon”. This was a reading aid for the blind, in which the operator scanned a printed page via an array of small vibrators on their finger.

      Taenzer had shown that a rolling display of only one character width was readable. In a preliminary experiment we showed that the reading speed increased as the number of characters displayed increased [Newell et al., 1975]. We thus conducted formal reading experiments using a simulated display between 1 and 12 characters long. We also compared rolling and walking displays (where the location of the character matrixes were fixed and the letters jumped from one matrix to the next). Users performed significantly better with the rolling display and, with a 5-character display, 99% of sentences could be read at a (fast typing) rate of 60 wpm [Newell and Brumfitt, 1979b].

      Figure 2.2: Early AAC Devices. (a) Portaprinter - commercially available; (b) TIC - developed by Rick Foulds, Tufts University, Boston; (c) AutoCom - developed by Greg Vanderheiden, University of Wisconsin-Maddison.

      Although a rolling display would be more expensive to produce, we decided that this was essential, and, as a compromise between cost and readability, we built a 5-character prototype using individual light-emitting diodes. This can been seen in Figure 2.3(a). A later version shown in Скачать книгу