1、W 3404583 0098383 T59 W ETSI 1 ECHNICAL REPORT ETR 096 August 1993 Source: ETSI TC-HF Reference: DTR/HF-I 002 UDC: 621.39 Key words: Human factors, PBI, computer services Human Factors (HF); Phone Based Interfaces (PBI) Human factors guidelines for the design of minimum phone based user interface to
2、 computer services ETS I European Telecommunications Standards Institute ETSI Secretariat Postal address: 06921 Sophia Antipolis Cedex - FRANCE Office address: Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE Tel.: + 33 92 94 42 O0 - Fax: + 33 93 65 47 16 0 European Telecommunications Stand
3、ards Institute 1 993. All rights reserved. No part may be reproduced except as authorised by written permission. The copyright and the foregoing restriction on reproduction extend to all media in which the information may be embodied. 3404583 0098382 995 H Page 2 ETR 096:1993 Whilst every care has b
4、een taken in the preparation and publication of this document, errors in content, typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to “ETSI Editing and Standards Approval Dept.“ at the address shown on the title page. 3404583 0098383 821 = Page 3 ETR
5、096:1993 Contents Foreword . 5 1 Scope . 7 2 References . 7 3 Definitions and abbreviations 7 3.1 Definitions . 7 3.2 Abbreviations 8 4 Principles . 9 5 Human factors guidelines . 9 5.1 User context 9 5.1.1 Commands . 9 5.1.2 Data entry 10 5.1.3 Menu 11 5.1.4 Prompt messages 11 5.1.5 5.1.6 Welcome m
6、essage . 12 5.2 System context 12 5.2.2 Dialogue structure . 13 5.2.3 Feedback . 13 5.2.4 Help 13 5.2.4.1 Error 13 5.2.4.2 Choice 14 5.2.4.3 Prompts 14 5.2.5 Navigability 14 5.2.6 Response times . 15 5.2.7 Time outs . 15 5.2.8 Types of users 15 Soft switch between pulsing and DTMF dialling . 12 5.2.
7、1 Cut-through 12 Annex A (informative): Screen Based Interface versus Phone Based Interface 17 A . 1 Some aspects provided from comparison with Screen Based Interfaces 17 Annex B (informative): Sound quality . 18 B.l Sound quality . 18 8.2 Audio coding choice 19 B.3 Message concatenation . 19 8.4 Sp
8、eaker choice . 20 B.5 Style . 20 B.6 Text to speech . 20 6.7 Music 21 History 22 I 3404583 0098384 768 Page 5 ETR 096:1993 Foreword This ETSI Technical Report (ETRI has been produced by the Human Factors (HF) Technical Committee of the European Telecommunications Standards Institute (ETSI), ETRs are
9、 informative documents resulting from ETSI studies which are not appropriate for European Telecommunication Standard (ETSI or Interim European Telecommunication Standard (I-ETS) status. An ETR may be used to publish material which is either of an informative nature, relating to the use or the applic
10、ation of ETSs or I-ETSs, or which is immature and not yet suitable for formal adoption as an ETS or an I-ETS. The purpose of this ETR is to provide guidelines for services providers, user interface designers, application writers, and human factors engineers, etc., in the development of a Phone Based
11、 Interfaces (PSI). The guidelines are intended to facilitate usage of new services by allowing users to transfer knowledge learnt in one application, and apply it in the use of another. What should not be assumed from these guidelines, is a wish to constrain development based on new and evolving tec
12、hnology. A significant number of the current 400 million telephones will become Dual Tone Multi Frequency (DTMF) based, as new digital exchanges are used in networks. This will provide a basis for customers to access a wide range of services such as: - voice mail; - banking; - shopping. information
13、retrieval; The challenge of application designers is to allow people who currently use these services through a Screen Based Interface (SBI), to achieve a similar degree of access with Phone Based Interface (PSI). The additional advantage is that Phone Based Interfaces (PSI) are still at an early st
14、age of market development. The opportunity exists for customers to be presented with varied services in a coherent framework. Previous page is blank - 3404583 0098385 bT4 Page 7 ETR 096: 1993 1 Scope This ETR is only concerned with Phone Based Interfaces (PBls) that assume DTMF input and speech outp
15、ut. Guidelines for the use of speech recognition as a means of user input are not considered as being within the scope of this ETR. The intention of this ETR is to achieve consistency across a number of core functions and facilities within PBls independent of either invocation by the user or applica
16、tion by different service providers. An example of the use of these guidelines to an application area is given. The guidelines begin to address the usability of PBls. To ensure that products and services meet the requirements of a particular market, usability testing and interactive design should be
17、 part of the product development process. It is to be remembered that in order to create a voice service, “expertise in ergonomics is often necessary, just as possessing a medical encyclopaedia does not suffice to cure a sick person“ (as stated in “Ergonomic criteria for the evaluation and design of
18、 user interfaces“ l I). 2 References For the purposes of this ETR, the following references apply: I 1 21 31 D. L. Scapin in Actes du XXVI Congrs de la SELF, Montreal, Canada, (1 990): “Ergonomic criteria for the evaluation and design of user interfaces“. CCITT Recommendation E. 183 (1 988): “Guidin
19、g principles for telephone announcements“. CCIlT Recommendations P.80 to P.84 (1 9881, Vol. 5: “Telephone transmission quality - Subjective opinion tests“. 3 Definitions and abbreviations 3.1 Definitions For the purposes of this ETR, the definitions and explanations of key terms and concepts used ap
20、ply. Application: set of files, programmes and processing procedures developed and organised to carry out a task automatically. Audiofax: data transmission service combining voice service and facsimile. Audiotex: several definitions exist: audiotex is either the generic term for all services, or sim
21、ply inquiry access services. Audiovideotex: data transmission service combining voice service and Videotex. Beeps: short audio warning signal produced by the system. Call transmission: ability of the system to make outgoing calls to a user. Coded speech: speech treated by coding algorithm. Coding: a
22、n operation transforming electrical signals from acoustic transducers into binary codes which can be transmitted or saved in mass storage devices. Concatenation: assembly mechanism of elementary messages (fragments of sentences, words or syllables) making up a voice message. Previous page is blank 3
23、404583 0098386 530 Page 8 ETR 096: 1993 Cut-through: systems capability to follow commands without waiting for their introduction or end thereof. Dial pulsing: the means of signalling generated by telephone rotary dial and some keyboards. Such signalling uses regular momentary interruptions at the s
24、ending end of the telephone line. Dual Tone Multi-Frequency (DTMF): multifrequency codes generated by touch-tone pads. Earcon (jingle): message, or fragment of message, generally based on repeating a musical theme and designed to trigger recognition. Ergonomics: adapting working conditions to man: i
25、mplementing human-oriented scientific knowledge, necessary for developing tools, machine and appliances that can be used by the greatest number of people with maximum comfort, security, and efficiency. Escape (Key): key allowing access to a second virtual keyboard allotting a different role to the k
26、eys. Incoming calls: ability of system to take user calls. Interactivity: principle which enables the user and system to exchange commands and messages. Linear (Dialogue): dialogue structure which, unlike tree-form dialogue, does not offer menu choice to the user. Data and operations are offered in
27、predetermined order. Navigation: the means of moving between a number of items, or even between a number of application branches. Pause detection: operation which tells system that the user has not spoken for “a while“ Prosody: modulation of length (sounds and pauses), of register and intonation wit
28、hin the language which make up the diction character. Speech detection: operation which tells systems that the user has begun to speak. Speech recognition: technique for detecting and interpreting voice commands from user. Text-to-speech: technique enabling the machine to restore data, supplied in t
29、ext form, in voice form. Tree form (Dialogue): dialogue structure based on consecutive menus. Voice command: any means of giving system voice commands (see Speech recognition and Speech detection). Voice messaging: deferred communication system enabling users to receive and transmit audio messages b
30、y telephone. 3.2 Abbreviations For the purposes of this ETR, the following abbreviations apply: CI Command Identifier DTM F Dual Tone Multi-Frequency PBI Phone Based Interface SBI Screen Based Interface W 3404583 O098387 477 Page 9 ETR 096: 1993 4 Principles The purpose of this Clause is to harmonis
31、e voice dialogue using telephone tone keys. Standard procedures are proposed, as well as the assignment, where possible, of each function to a telephone key. Consistency reinforces learning and as a result, makes using voice services easier. Eight general principles are defined here: Commands Help U
32、ser control NOTE 1: Cancelling Delimiter Confirmation Security Feedback NOTE 2: Defined functions should be invoked with the same command and, where possible, in different contexts the same command should invoke similar functions. Commands can be invoked with more than one key press, menu items shou
33、ld be considered as single key entries, where possible. Help should always be available and it should be context sensitive. The user should always be in control, and should not be constrained by the system or service. The user should have the ability to “cut through“ a prompt and to dial ahead as we
34、ll as offering BACK STEP function and a return to a main menu function. Enable the user to cancel data entry, or actions that a user cannot recover from. Where data is of unpredictable length, then either a # or time out should be used as a delimiter. Where an action is deemed to be irreversible, al
35、ways present the user with a system message that asks the user for confirmation and ensure that the correct confirmation message is selected. The log-on procedure is an implementation issue, and is outside of the scope of this ETR. The system, or service should confirm user action and input. Where i
36、nvalid keys or commands are selected feedback should be given to the user. The feedback should be on both a key-by-key basis, and when an action has been completed. 5 Human factors guidelines The following guidelines are presented in alphabetical order, and encompass good human factors practice. 5.1
37、 User context 5.1.1 Commands Commands and entries are made on a telephone keypad and where commands are accessed as part of a menu structure, then the normal rules of menu structure apply. Using letters mnemonically to indicate a function or command should be avoided as this can rapidly lead to ambi
38、guities or to badly adapted word choices. Where commands are accessed directly from the keypad, outside of the menu structure, then the following applies. 3404583 0098388 303 Page 10 ETR 096:1993 Basic interaction with the service These should be provided at all times. Command Identifier (Ci) * I is
39、 to be used when there are more than six items in a menu: - help “O; - language for further study; - back step for further study; main menu for further study; - cancel *I*. It is generally recommended that commands associated with PBI are assigned to the keypad such that the left hand column of the
40、keypad indicates regressive steps, the right hand column indicates progressive steps, and the centre column indicates the status of the system. Specific commands: example of voice mail: rewind; - fast forward; pause; - stop; - delete; - playbackhepeat; confirm; edit/continue. 5.1.2 Data entry Decima
41、l numeric data entry is preferred to alphabetic data entry. However, some PBI applications require alphabetic or alpha-numeric entries. EXAMPLE 1: The application requires one input to define a key and a subsequent input to define the position of a character on that key. “ETSI“ would be coded: 32 81
42、 73 43. EXAMPLE 2: The application requires a single input to define a key which represents a number of characters. The application can search for appropriate characters by matching each keystroke in turn with previous keystrokes, searching for a matching string in the database. Since the same keyst
43、roke may create different valid strings, the application should confirm the selection by voice feedback. “ETSI“ would in this case be coded only by: 3874. A method may be required for entering alpha numeric strings of varying length. It may be necessary to signal to the service the mode in which the
44、 user is signalling (.e. alpha or numeric). EXAMPLE 3: The application requires the entry of both alphabetic and numeric data. In this case the delimiter key # 1 should be used to define the boundary between alphabetic and numeric input (for a customer password, some credit card numbers, etc.). It i
45、s unnecessary to feedback the individual characters that have just been entered to the user. However, confirmation of input should be given where modification of data input or termination of input has occurred. Entries of unpredictable length need a delimiter. For consistency, the delimiter when the
46、re are entries of unpredictable and predictable length in the same application. # I can be used Cancellation of the current entry should be enabled by a single command. Offering character-by-character correction is tedious. E 3404583 0098389 24T E Page 11 ETR 096: 1993 For entry of long data strings
47、, it may be useful to break up the request. User inactivity at the beginning of, and during entry, will be considered as a time-out. 5.1.3 Menu (See cut through, time outs). Menu options should be presented to the user such that commonly selected options require the shortest available key sequence.
48、Where possible, menu options should be assigned in a logical order starting on key 1 I. At all times the difference between menu options available the dialogue and commands available through the keypad should be distinguished. Where keys have pre-assigned functions on the keypad, as in an applicatio
49、n, then care shall be taken in assigning the remaining additional keys to menu options. In general, no more than six options should be assigned to a menu that have no pre-assigned functions to a keypad. In instances where there is a necessity to have a user access generic function such as help, both implementations outlined above would then use the * 1 key to “escape“ to an underlying functionality assigned to the keypad. If a menu is not given, then there should be some means of offering the user a prompt, either explicitly or implicitly. 5.1.4 Prompt messages The interact
