# Usability Analysis of Smart Speakers from a Learnability Perspective for Novel Users
###### Abstract  
Although commercial smart speakers are becoming increasingly popular, there is still much potential for investigation into their usability. In this study, we analyzed the usability of commercial smart speakers by focusing on the learnability of young users who are not yet familiar with voice user interface (VUI) operation. In the experiment, we conducted a task in which users repeatedly operated a smart speaker 10 times under four conditions, combining two experimental factors: the presence or absence of a screen on the smart speaker and the operation method (voice control only or in conjunction with remote-control operation). The usability of the smart speaker was analyzed in terms of task-completion time, task-completion rate, number of errors, subjective evaluation, and retrospective protocol analysis. In particular, we confirmed and compared the learning curves for each condition in terms of the performance metrics. The experimental results showed that there were no substantial differences in the learning curves between the presence and absence of a screen. In addition, the \"lack of feedback\" and \"system response error\" were identified as usability problems, and it was suggested that these problems led to \"distrust of the system\". smart speaker; voice user interface; learnability; learning curve; usability; retrospective protocol analysis +
Footnote †: journal: _J. Stat. Innova_  
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study. In addition, many consumers are not accustomed to VUI operation at present, as physical operation is still mainstream. Improving learnability is also an important issue. Several studies [10; 11; 12] have considered how to improve learnability and reduce the memory burden in VUIs. However, these studies have focused on solution proposals and their evaluation, considering aspects other than the learnability of commercial smart speakers. Since commercial smart speakers are expected to spread rapidly, it is necessary to examine their usability from the perspective of users who are unfamiliar with VUIs, considering how they will learn to operate commercial smart speakers. Another advantage of commercial smart speakers is that they can control other compatible devices. However, regarding the control of other devices connected wirelessly, not all of them are necessarily voice-controllable, and it is necessary to use the remote control of the device at the same time. For example, many companies have released home appliances that are compatible with Amazon Alexa. Amazon Fire TV is a typical example of such a product, operated in conjunction with a remote control. This represents a usability issue unique to commercial smart speakers. There are many usability problems in VUIs because it is impossible to transfer the knowledge of GUI design that has been cultivated thus far [13; 14]. As described above, the issues unique to VUIs cannot necessarily be captured by the conventional usability evaluation framework [14]. In other words, the lack of knowledge and guidelines regarding the usability issues unique to VUIs makes it difficult to conduct effective design development [15; 16; 17]. The usability studies on VUIs to date include studies that examine the usability problems of VUIs and studies that develop usability evaluation indices for VUIs. The studies that examine the usability issues in VUIs and try to improve them are mostly focused on the VAs of smartphones or other computers in specific fields, such as the elderly [18; 19], health [20; 21], education [22], tourism [23], medication support for the elderly [24; 25], and so on. Although there are some studies targeting general users' use of commercial smart speakers and VAs [5; 6; 8; 9; 13; 26; 27], there are few usability evaluation studies focusing on the learnability of users who are unfamiliar with VUIs and how they become proficient in operating commercial smart speakers.