Since the smartphone has become a permanent and versatile companion in everyday life, it is believed that mobile learning will become even more important. According to a Trend Study 2016, 86 percent of the e-learning experts surveyed see mobile applications/apps as the most economically successful learning format in the coming years. 
Mobile learning as a complement to traditional mediaThere exist different definitions of mobile learning. But there are two distinguishing features: the possibility to learn everywhere and at any time, and the use of mobile devices (primarily smartphones and tablets rather than laptops). Thus, the mobility of the learning location and the technological support of learning are at the forefront.  Some even say that mobile learning should take device-specific features (e. g. the camera or the position sensor) into account, but this refers more to the design of mobile learning content. Mobile learning itself should not be a substitute for traditional learning media or e-learning but should be a sensible alternative to it.
At the same time, there is a disadvantage : If spontaneous learning is to be made possible, the content must be designed accordingly. After all, spontaneous learning often only takes place for a short time and is often interrupted.
Advantages and disadvantages of mobile learning 
|- learning anywhere anytime
- individual learning speed
- high familiarity with the smartphone
- use of different media (image, sound, video)
- combinable with databases, forums, chats
|- high development costs
- high self-learning competence required
- concentration problems
- low processing depth of the learned material
Media for mobile learningMobile learning is possible in any media format that can be used on a smartphone/tablet in a user-friendly manner. Text as (enhanced) EPUB or PDF and video is just as much a part of it as audio content. Audio content offers a number of benefits for mobile learning. It is certainly interesting for the user that they can "subscribed to" it in the form of a podcast, so you don't have to worry about the updates yourself every time. Podcasts have been around for about 10 years. They are, for example, very successful in the entertainment sector (see the media libraries of public broadcasters). They are not so widespread in the field of specialist information, especially when compared with visual content. This may also be due to the fact that the auditory channel is not believed to be as efficient as the visual channel. Here are two examples why.
"I'm more of a visual learner."Since the 1970s, classifying learners to certain typologies is still very popular (e. g. in the German-speaking world according to Vester's typology : auditive, optical-visual and haptic-cognitive). According to this and similar theories, each learner has a dominant/preferred "channel" on which he or she receives and processes information particularly well. Those who are of the auditory type should, therefore, learn best by listening. In order to enable successful information processing, the information must, therefore, be prepared according to type. However, learning research could not find any empirical evidence. Ok, each learner is different and, yes, there may be learners who prefer to read something rather than listen to it. But the specific link with learning performance could not be established. On the other hand, there is a clear connection with the learning topic: Suppose someone were to ask:"I want to teach you something. What would you prefer: a series of illustrations, a text, a podcast or a performance in the form of movements?" Who would answer the question immediately and not ask first what to learn: an equation, a song or a dance? 
"20% is what you keep when you hear..."The following statement is no less problematic: The learning success increases to the extent that several sensory channels are used simultaneously in learning:
- 20 percent is retained when listening
- 30 percent for vision
- 50 percent when you see and hear the learning material
- 70 percent when you see, hear and talk about it, and
- 90 percent when you see it, hear it, talk about it and become active yourself.
One practical consequence of this is that video beats audio. But that is not tenable. Because in the "learning pyramid" two completely different concepts are mixed. On the one hand, it is the "cone of experience" by Dale. In 1946 he proposed a continuum - and no hierarchy - of different teaching methods. In the meantime, it has been proven that there is no "superior method", but that all methods can be effective depending on the context.  The percentages, in turn, can be traced back to an article in the Journal of Education (Boston, 1913). The figures show the significance of learning for action within the context of Montessori pedagogy. Unfortunately, the figures do not stand up to empirical examination. 
Special features of listeningOf course, listening compared to reading has a number of special features - not least from the practical point of view of the learner. For example, if attention fluctuates, then it is easy to return to any place when reading. This is not possible without interrupting a lecture in real time. In the case of a recording, the problem arises to get back to the correct position with the controller.
But listening can be combined with other activities. This includes simple mechanical tasks such as jogging and cleaning up, but also complex automated tasks such as driving a car. The prerequisite, however, is that the content has been prepared in a correspondingly structural and linguistic manner. This is demanding for the producers.  For print media, there are a number of structuring options: Structures are conveyed by means of subheadings, meaningful connections are established by means of paragraphs and enumerations are indicated by a bullet. Graphics help to illustrate complex correlations. In graphics, in turn, certain parts can be highlighted to facilitate understanding. The importance of these cues to understanding is already known to adults. Cueing is also possible for audio media (e. g. modulation, speaker change, jingles, dramatization etc.). Unlike an indent in a list, the meaning of the cue is not clear from the outset. It must be learned while listening.
TakeawayPerceiving is not learning. In order to learn something, simply put, a meaning must be taken from the sensory impression, it must be combined with previous knowledge and stored in a retrievable memory. For many people, seeing is a dominant channel. However, it does not always prove to be the optimal channel in every situation. Audio media can be particularly effective as part of a media mix. They supplement e. g. print media for self-instruction (as audio files of a language course). Audio media can also be used to prepare and follow up knowledge offers (record a lecture or textbook). Well-edited audio content, e. g. with elements of dramatization, also has a motivational effect.  Especially those who travel a lot can use idle time to keep up to date. Short, self-contained units are particularly suitable for this purpose.
 mmb Trendstudie (2016): Die Zukunft gehört dem Mobile Learning. Link
 Traxler, J. (2009): Current State of Mobile Learning. in Ally, M. Mobile Learning Transforming the Delivery of Education and Training. Link
 Krauss-Hoffmann, P., Kuszpa, M., Sieland-Bortz, M. (2007): Mobile Learning - Grundlagen und Perspektiven. Link
 Vester,F.(1975) Denken,Lernen,Vergessen.Stuttgart. Deutsche Verlagsanstalt GmbH
 Riener, C., & Willingham, D. (2010). The myth of learning styles. Change: The magazine of higher learning, 42(5), 32-35. Link
 Lalley, J. P., & Miller, R. H. (2007). The learning pyramid: Does it point teachers in the right direction? Education, 128(1), 64.
 Betrus, A. (2016). The Corruption of Dale's Cone of Experience Link
 Schmidt, C. (2014): Podcasts in pädagogischen Kontexten: Einsatzmöglichkeiten und effektive didaktische Ausgestaltung innovativer Audiomedien. Diplomica Verlag GmbH, Hamburg.