Interaction Devices: Output Devices

1. Interaction Devices:Output Devices Lecture 12 Date: 9th March

2. Overview of Lecture • Visual output – screens: CRT , LCD, projector • Sound output • suitable for specific application scenarios • speech synthesis – uses concatenation or synthesis-by-rule • speech applications

3. Interaction Device Introduction Interaction Devices Input Devices Output Devices

4. Output Devices • Output devices are those devices that convert the computer’s response in a form perceptible by a human, known as output • Wide range of output techniques, each of which has advantages and disadvantages depending upon the context in which they are used • Output devices can be categorised into : • Visual Output devices • Sound Output devices

5. Visual Output Devices • Visual output using a screen is by far the most common form of output today • The display has become the primary source of feedback to the user from the computer • The display has many important features, including: • Physical dimensions (usually the diagonal dimension and depth) • Resolution (the number of pixels available) • Number of available colors, color correctness • Luminance, contrast, and glare • Power consumption • Refresh rates (sufficient to allow animation and video) • Cost • Reliability Visual Output Devices

6. Visual Output Devices • Raster-scan cathode-ray tube (CRT) • Liquid-crystal displays (LCDs) • Projectors • Printers Visual Output Devices

7. Visual Output Devices - CRTs • Most comment screen technology is the Cathode Ray Tube (CRT) screen • + Cheap • + Can support rapid animation • + High colour capability • - Bulky device • - Has associated health risks – radiation concerns. Flicker, poor legibility and low contrast can cause eyestrain and fatigue Visual Output Devices

8. Visual Output Devices - LCDs • Light, flat plastic screens • + Smaller (than CRTs) • + lighter (than CRTs) • + use less power (than CRTs) • + no radiations problems • + Less tiring than c.r.t. displays, and reduce eye-strain, due to reflected nature of light rather than emitted • Typically used in personal organiser or notebook computer Visual Output Devices

9. Visual Output Devices - Projectors • Projects output from computer onto another medium • Useful for where output is required for a group rather than an individual • Wide range in quality. High end projects can cost up to £10,000 Visual Output Devices

10. Visual Output Devices - Printers • Popular printing technology builds up characters on page, as on the screen, as a series of dots: • dot-matrix printers • inkjet printers • thermal printers or fax machines • laser printers • color printers • photographic printers Visual Output Devices

11. Sound Output • Sound Output devices • Application scenarios • Speech synthesis – uses concatenation or synthesis-by-rule • Speech applications Sound Output Devices

12. Sound Output Devices • Speakers • Various types of speakers e.g. Common coil and cone, Electro static, Direct digital speaker • Headphones Sound Output Devices

13. Application Scenarios • Applications where sound complement a visual interface (e.g computer games) • Applications where for alerting and feedback purposes are required (e.g. incorrect action alert) • Applications where eyes are engaged another task (e.g. flight decks) • Applications where background processes need to be monitored (e.g. disk access noise when saving a file) • Applications for blind or partially sighted users • Applications for illiterate users • Applications for users with limited mobility Sound Output Devices

14. Speech Synthesis • Speech Synthesis: The process of automatic generation of speech output from data input which may include plain text, formatted text or binary objects. Text-to-speech generation is an example of speech synthesis (W3C) • Two methods of speech synthesis: • Concatenation • Synthesis-by-rule Sound Output Devices

15. Speech Synthesis • Concatenation: • Digital recordings of real human speech are stored by the computer • May be stored as sentence, phrase or word segments • Usually applied to applications with small vocabularies of 200 words or less • Example: “the number you require is …” • Demo – personal organiser demo Sound Output Devices

16. Sound Output Devices • Synthesis-by-rule • Does not use recorded human speech • Is commonly used in text-to-speech • a set of rules of phonemes and rules relating to the context of a sentence or phrase is used to synthesis works and sentences • When used with databases, has potential forproducing much larger range of responses than speed produced by concatenation. • Can sound artificial • Useful where larger vocabularies are required. Sound Output Devices

17. Sound Output Devices • Synthesis-by-rule • Phonemes • Are used for speech generation using synthesis-by-rule • are used where the words needed for the application cannot be predicted in advance • ~40 phonemes in English, e.g., the words “bad” and “had” differ in their initial phoneme. Sound Output Devices

18. Speech Applications • So far, have discussed speech as an input (speech recognition) and speech as a type of sound output (using speech synthesis) • Applications that use speech recognition and/or speech synthesis are called speech applications Sound Output Devices

19. Speech Applications – Hardware Requirements • In order to use a speech application, computer must have • Microphone (for audio input) • Sound card (for audio reproduction) • Digital signal processor card (some some Speech recognition systems • Speaker (for audio output) • Headphones (for audio output) • Adequate processing power • Adequate memory

20. Speech Applications – Specific Software Requirements • Speech recognition engine • Speech synthesis (e.g. text-to-speech engine)

21. Screen Readers • Screen readers - software that works together with a speech synthesizer to read aloud everything contained on a computer screen, including icons, menus, text, punctuation, and control buttons. • Useful for visually impaired or blind users • Useful for illiterate users • Useful for users with impaired mobility • Sample screen readers: • JAWs by Henter-Joyce (http://www.hj.com/) • Microsoft Narrator- supplied with Windows operating system • Home Page Reader by IBM (http://www-3.ibm.com/able/hpr.htm) • ReadPlease (http://www.readplease.com/)

22. Speech Application Technologies • There are a range of mark-up languages available that enable speech applications to be used in combination with the web • Examples: • VoiceXML • CallXML • SSML • SALT • Also have the Java Speech API for incorporatingspeech into java applications, including those builtfor WWW.

23. Voice XML • Allows users to use a web application by speech recognition from the user using a microphone • Also allows applications that are accessed by telephone • VoiceXML-enabled applications read Web pages to the user, and allow the user to respond by talking • Applications require a VoiceXML interpreter on the server side and VoiceXML browser on the client • More at http://www.w3.org/TR/voicexml/

24. Voice XML example The system asks for 2 pieces of information year of birth and day of birth: <?xml version="1.0"?> <vxml version="2.0"> <form> <field name="birth-year"> <prompt>In which month were you born?</prompt> <option>January</option> <option>February</option> <option>March</option> <option>April</option> <option>May</option> <option>June</option> <option>July</option> <option>August</option> <option>October</option> <option>November</option> <option>December</option> </field> Next page…

25. Voice XML Examples <field name="birth-date" type="number"> <prompt> On what day of <value expr="birth-year"/> were you born? </prompt> </field> <block> <submit next="http://www.voicexml-example.com/birth-info.vxml "/> </block> </form> </vxml>

26. SALT • Speech Application Language Tags • Tags extend other markup languages e.g. (X)HTML, WML. Can’t use SALT tags on their own. • Can enable existing Web applications for speech • Users can use telephone or multimodal devices such as PCs, notebooks, tablets, cell phones and wireless PDAs. • Simple and fast to implement • Seven tags in total, including: • <PROMPT> - Plays speech output (speech synthesis) • <LISTEN> - “takes in” speech (I.e. speech recognition tag)

27. SALT Example • http://msdn.microsoft.com/library/default.asp?url=/library/en-us/SASDK_B4_SALT/html/ST_prompt.asp

28. Call XML • Created by Voxeo • Assists visually impaired users by providing access to web pages from the telephone • XML-based mark-up language • Examples for applications: voicemail, interactive voice response systems

29. Speech Synthesis Mark-up Language (SSML) • Currently under review by World wide web consortium (W3C) • An XML-based markup language for assisting in the generation of text-to-speech in Web and other applications • Provides standard ways of controlling and specifying speech characteristics such as pronunciation, volume, rate, tone • Can be embedded within VoiceXMl and SALT • More at http://www.w3.org/TR/speech-synthesis/

30. Java Speech API (JSAPI) • Version 1 released in 1998 • API to allow java applications and applets to use speech at the user interface – supports both speech recognition and speech synthesis – javax.speech • Speech applications can be written completely in java • Includes a mark-up language, Java Speech API markup language (JSML) to adjust speech synthesis (e.g. tone, volume etc) • Example overleaf is of the method required to generate speech.

31. JSAPI – code sample public void MySpeech(String SpeakText){ try { // Create a synthesizer for English Synthesizer synth = Central.createSynthesizer(new SynthesizerModeDesc(Locale.ENGLISH)); // Get it ready to speak synth.allocate(); synth.resume(); //Speak Now... synth.speakPlainText(SpeakText, null); // Wait till speaking is done synth.waitEngineState(Synthesizer.QUEUE_EMPTY); // Clean up synth.deallocate(); } catch (Exception e1) { System.out.println("EXCEPTION in MySpeech :" + e1); } } …… Later…. In application, to “speak out” text just call the method with the text to be spoken: MySpeech(customerName);

32. Summary of Lecture • Input Devices • Text entry devices • Keyboards – QWERTY, Alphabetic, Chord, Dvorak, Braille • Handwriting Recognition • Speech Recognition • Positioning and pointing devices • Direct control devices • Indirect control devices • Devices for disabled • Output Devices • Visual output – screens: CRT , LCD, projector • Sound output • suitable for specific application scenarios • speech synthesis – uses concatenation or synthesis-by-rule • speech applications References

33. Terms of Reference • Shneiderman, B. & Plaisant, C. (2005) Designing the User Interface • Preece, J. et al. (2002) Interaction Design • Benyon, D. et al (2005) Designing Interactive Systems • Helander, M. et al (1997) Handbook of Human-Computer Interaction • Norman, D. (1990) The Design of Everyday Things References