1、REPORT ETR 051 December 1992 Source: ETSI TC-HF Reference: DTR/HF-3002 UDC: 621.39 Key words: Usability, checklist, telephones Human Factors (HF); Usability checklist for telephones Basic requirements ETSI European Telecommunications Standards Institute ETSI Secretariat Postal address: 06921 Sophia
2、Antipotis Cedex - FRANCE Office address: Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE Tel.: + 33 92 94 42 O0 - Fax: + 33 93 65 47 16 - Tlx: 470 040 F 0 European Telecommunications Standards Institute 1 992. All rights reserved. No part may be reproduced except as authorised by written p
3、ermission. The copyright and the foregoing restriction on reproduction extend to all media in which the information may be embodied. 3404583 0068320 081 = Page 2 ETR 051:1992 Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical or oth
4、erwise, may occur. If you have comments concerning its accuracy, please write to “ETSI Standards Management Dept.“ at the address shown on the title page. 3404583 00b8L2L TL8 Page 3 ETR 051:1992 Contents Foreword . 5 1 Scope . 7 2 References 7 3 The usability component model 8 4 Usability checklist
5、framework . 10 4.1 Context of use . 10 4.2 Intended usage . 10 4.3 Intended users . 10 4.4 Environmental requirements for use . 10 5 Identification of usability components 11 6 The usability checklist 12 6.1 12 6.2 13 6.3 Statement 3: Physical dimensions of dial/key pad . 13 6.5 Statement 5: Electro
6、-acoustic sensitivity for sending and receiving . 13 6.7 Statement 7: Size of numbers and letters on dial/push buttons 14 Statement 1 : Size and shape of the handset Statement 2: Weight and balance of the handset . 6.4 Statement 4: Acoustic level of signalling tones . 13 6.6 Statement 6: Sidetone at
7、tenuation . 14 6.8 Statement 8: Key pad lay-out . 14 6.9 Statement 9: Push button operation feed-back . 14 6.1 O Statement 1 O: Incoming call indication . 15 6.1 1 Statement 1 1 : Answering and terminating a call 15 Annex A (informative): Usability checklist for telephones . list of additional infor
8、mation 16 History . 17 . = 3404583 O068322 954 = Page 5 ETR O51 :1992 Foreword ETSI Technical Reports (ETRs) are informative documents resulting from ETSI studies which are not appropriate for European Telecommunication Standard (ETS) or Interim European Telecommunication Standard (I-ETS) status. An
9、 ETR may be used to publish material which is either of an informative nature or is not yet suitable for formal adoption as an ETS or I-ETS. This ETR has been produced by the Human Factors (HF) Technical Committee of the European Telecommunications Standards Institute (ETSI). A users acceptance of n
10、ew telecommunication services and products depends on their usability. Usability can be defined in terms of its two main components, performance and satisfaction. It is important to apply usability principles in all phases of the product development process. In the checklist a number of usability co
11、mponents of a simple telephone set are identified, and each of them are checked against a set of statements, which encapsulate good human engineering principles. These principles are based on standards, guidelines and empirical knowledge relevant to the specific user-interface for achieving a high d
12、egree of usability. This ETR includes a model for identification and structuring of the usability components which influence the usability of the specific user-interface. In this ETR, this methodology has been applied to develop a usability checklist for a user-interface consisting of a simple telep
13、hone set. At an early stage of the usability evaluation process the usability checklist can be used to obtain a rough estimate of the usability of the telephone interface. This is done by checking the degree of conformance between relevant usability components of the user-interface and agreed design
14、 rules. Elaboration of the usability checklist methodology could be done by applying an application dependant Weighting factor to each of the usability components identified. Comparison of different user interfaces could then be expressed by single usability measures. It is intended to treat the spe
15、cial requirements of users with disabilities in a separate ETSI publication. Previous page is blank 3404583 00b8123 890 Page 7 ETR 051 A992 1 Scope . In general, a usability checklist is based on standards, guidelines and empirical knowledge of what are good human engineering principles relevant to
16、a specific user-interface. The usability checklist represents a set of minimum requirements to the usability components identified. Final usability evaluation of a product may still be needed e.g. by using ETSI DTR/HF-3001 Ill. The usability checklist for telephones is aimed at: - developers of tele
17、phone sets; - procurement staff for including usability requirements in their specifications; - customers and consumers associations producing test reports. One problem in usability evaluation is the very large number of components that may influence the usability. Therefore, this ETR includes a mod
18、el suitable for structuring the usability components of user-interfaces. The checklist methodology is demonstrated for a user-interface consisting of a simple telephone set having the following basic functions for user task performance: setting up a call; receiving a call; performing voice communica
19、tion; terminating a call. The user-interface of a simple telephone set supports the service “voice telephony“. During the set up of a call, information is exchanged between the user and the system (network). Some of this information is presented to the user as tone signals or spoken messages. Since
20、this specific issue is studied by another group in ETSI, only “telephone set-related“ usability components of the user-interface are included in the checklist. Similarly special requirements for users with disabilities will be discussed in another OATS publication. Checklists for other types of user
21、-interfaces, e.g. business telephony, interactive information services, store-and-forward messaging, and network management and system administration may be developed by applying the structural model. 2 References For the purposes of this ETR, the following references apply: 11 1 ETSI DTR/HF-3001: “
22、Guide on usability testing methods for telecommunication terminals and services“. 21 CCIlT Recommendation P.35 (1 988): “Handset telephones“. i31 i41 Applied Ergonomics (1 9881, 19.4, 271 -274: “Weight and balance of a new telephone handset“, E.T. Klemmer 3,l KHz telephony teleservice, Attachment re
23、quirements for handset terminals (Candidate NET 33)“. 3 The usability component model The usability of a user-interface is related to specified users and to specified tasks in a specific environment. The usability measure contains information on how well the interfaceher combination is adapted to pe
24、rform the task (the performance measures) and information on the users attitude working with the interface (the attitude measures). More detailed information on the definition of the usability concept is contained in ETSI DTVHF-3001 11 I. Designing and usability evaluation of a product includes the
25、consideration of a large number of usability components each adding to the total usability of the product. m 3904583 0068325 663 m Page 9 ETR 051:1992 To be able to identify the relevant usability components, the following 3-dimensional model is used. The 3 dimensions are: user capabilities, user-sy
26、stem interface and application domains. The user capabilities may be described by: - anthropometric factors, related to the measures of the human body; - motoric factors, related to the muscular strength of the human body; * - perceptual factors, related to human perception, e.g. visual, auditive an
27、d tactile; - cognitive factors, related to processes in the human brain, e.g. thinking, learning, remembering and similar processes. User-system interfaces may be described by: - physical interface, e.g. keyboard design, function buttons or graphic capabilities; - user input/output, terminal display
28、 and user input, e.g. screen displays, core commands or standard error messages; - user-interface dialogue, covering dialogue functions, application and communication functions, e.g. expressed by the menu structure or the state transition control. For the application domain a number of related user-
29、interface concepts can be identified e.g.: - simple telephone set; - business telephony; interactive information services; - store-and-forward messaging; - network management and system administration; realising that no single user-interface concept is appropriate for all application domains. Graphi
30、cally, the usability component model can be expressed as shown in figure 1. Each cell on a frame represents a specific set of interfacehser capability relations and each of the frames represent a user-interface related to a specific application domain. A usability checklist for simple telephone sets
31、 should as a minimum include those usability components represented by the cells marked with full circles. For more complicated telephone terminals, such as business telephones interworking both with branch exchanges and with the public telephone network or with mobile communications systems, the us
32、ability components represented by cells marked by broken or dotted circles should be included. m 3404583 0068326 5TT m Page 10 ETR 051 : 1992 . Network management. Application Store-and-forward messaging . Domain Interactive information servic Business telephone Telephone set User-interface dialogue
33、 User/System User input- output Interface Physical interface Anthropometric . Motoric . Perceptual . Cogni ti ve User Capabilities Figure 1 : The usability component model 4 Usability checklist framework When applying a usability checklist to a specific user-interface, information on user capabiliti
34、es, the application performed and the specific environment shall be stated. For a usability checklist for simple telephones the following is specified: 4.1 Context of use A simple telephone set is intended for use in an office or household environment. 4.2 Intended usage For the sake of simplicity,
35、only the “generic“ functionality of a telephone set is considered: - setting up a call; - receiving a call; - performing voice communication; - terminating a call. 4.3 Intended users It is assumed that the users have learned the meaning of the tone signals and spoken messages used in the network. Th
36、ey also know the necessary procedures for operating the telephone set. Special requirements of users with disabilities are not specifically addressed in this ETR. 4.4 Environmental requirements for use. The telephone set is intended to be used in an environment where the physical access to the instr
37、ument, the light setting, the acoustic room noise level and electromagnetic disturbances do not have an impact on the functionality of the instrument. 3404583 0068127 43b Page 11 ETR 051 :1992 5 Identification of usability components For each of the applications it is possible by using the usability
38、 component model, to identify the usability components contributing to the usability of the telephone sets user-interface. Setting up a call - lifting the handset. Physical interface/anthropometric factors: - - - shape of earpiece. size of handset relative to human hand; weight and balance of handse
39、t; User input - outputlperceptual factors: - acoustic level of signalling tone. Setting up a call - entering a telephone number. Physical interface/anthropometric factors: - physical dimensions of dial/key pad. Physical interface/motoric factors: - forces needed to activate dial/key pad buttons. Phy
40、sical interface/perceptual factors: - identification of numbers and letters related to dial/key pad buttons. User input - output/perceptual/cognitive factors: - feedback (nature and timing) from push button activation. User-interface dialogue/cognitive factors: - key pad configuration. Setting up a
41、call - call progress. Ler input - output/perceptual factors: - acoustic level of tone signalling. Receiving an incoming call. Physical interface/anthropometric factors: size of handset relative to human hand; position of handset on the telephone set. - Physical interfacehnotoric factors: - weight an
42、d balance of handset. W 3404583 O068328 372 Page 12 ETR 051:1992 Physical interface/cognitive factors: identification of the handset. User input - output/perceptual factors: - acoustic level of telephone bell/tone ringer, or perceptual characteristics of visual alerting signal. User input - output/c
43、ognitive factors: - understanding of incoming signal. Performing voice communication. Physical interface/anthropometric factors: - shape and weight of handset. User input - output/motoric factors: - speech level needed for proper operation of the microphone. User input - output/perceptual factors: -
44、 acoustic level of speech signals in the telephone. Terminating a call. Physical interface/anthropometric factors: size and form of the cradle in relation to the handset. 6 The usability checklist Based on the above analysis, a usability checklist for a handset telephone set with basic telephony fun
45、ctions has been developed. The checklist contains a number of statements and includes references to standards, guidelines and agreed design rules, for which each statement is known to assure good user performance and user satisfaction. 6.1 Statement 1 : Size and shape of the handset A usability goal
46、 is that the handset shall be convenient to hold in the hand during conversation. The size of the handset shall allow sufficient room for the fingers that hold it. The shape of the handset shall make it possible to place the receiver and the microphone correctly relative to the human ear and to the
47、human mouth. The shape of the earpiece shall The size and the shape of the handset can be evaluated in comparison with CCITT Recommendation P.35 121. . m 3404583 0068129 209 m Page 13 ETR 051 :1992 6.2 Statement 2: Weight and balance of the handset - The weight of the handset has a preferred value i
48、n the range 150 to 200 grammes (excl. weight of the cord), and the preferred balance is the weight being distributed equally between the microphone end and the receiver end. See E.T. Klemmer and K.A. Haig: “Weight and balance of a new telephone handset“. Applied Ergonomics 1988, 19.4, 271 -274 31. 6
49、.3 Statement 3: Physical dimensions of dialkey pad The usability goal is that the signalling from the dial or from the key pad of the telephone instrument is performed without any errors caused by imprecise stopping of the dial or by the user pressing two or more buttons at the same time. A “pip“ on the “5“ button may improve orientation on the key pad. Key-pad dimensions can be evaluated in comparison with ISO/DP 9241 part 4 i41. 6.4 Statement 4: Acoustic level of signalling tones The usability goal is that the signalling tone is presented to the user at an acoustic level sufficient
