6. Discussion and conclusion
Although the auditory information in m-learning can be an important resource for delivering knowledge and information, there has been little research on how to design auditory instructions. In this respect, this study contributes to the auditory design research field in a little explored area. In particular, this study adds to the field by considering how the affordability and limitations of different devices affect the design. This study showed that the auditory design guidelines reflecting the mobility and personalization of m-learning were both effective and satisfactory. The final revised guidelines are as shown in Table 7. These guidelines emerged from a thorough process of the development of the initial guidelines, 1st and 2nd expert reviews, usability evaluation, 3rd expert review, and field evaluation. Expert reviews and usability evaluation were conducted for an internal validation, and the auditory design guidelines were modified and supplemented in the academic and practical perspectives of the experts and instructional designers. The revised guidelines form-learning content and their effectiveness in supporting learning underwent an external validation. The field evaluation method used in this study can be useful for examining the learning effects considering the mobility and personalization of m-learning. Previous studies were conducted mostly in laboratory settings or while walking outside (Brewster, 2002; Walker & Brewster, 2000), but these attempts did not involve natural settings and they failed to consider the wide range of factors in the external environment. Therefore, they may be unsuitable for examining a mobile environment. Accordingly, the research participants were recruited and asked to learn with a specific m-learning application either while on the move or in public places, such as a cafe. Considering that the aim of study was to develop auditory design guidelines based on the mobility and personalization of the m-learning environment occurring in public places, the field evaluation method, although unable to control the individual learning environment, can provide more meaningful information than a laboratory setting.