Audiobooks are generally a neglected/emerging area in much of the world. If one is in the US, of course it is less of a problem, but even Apple has a half-assed approach currently.
Apple / iOS / OSX
While it appears Apple is trying to get its act together, it is a far distance from right just yet: - On iOS audiobooks are now in iBooks (great!) - On OSX that is not the case. And no iBooks on Windows, much less Android. - Many countries are still not supported for audiobooks (in ibooks AND itunes), as well as various video formats Audible is the only lifesaver. Akin to Kindle for ebooks, with apps for every device, and it happens to be the only way to get an audiobook into Amazon and iTunes (and Audible itself, which has good apps). Note that Audible appears to get around the iTunes country restrictions for content, because the purchase is made at Audible.com (or other market) and then Audible apps are used for play. However, the download via iTunes option that is offered for OSX or other uses likely will fail because of the geographical restrictions at iTunes).
Android / Google Play Books / Google Play Music
This is of course the worst situation. Audiobooks are in the Music section, and of course some countries do not have music supported (such as Thailand and others). So no audiobook market. Horrible, just horrible. I suppose the best thing is to go through a third party such as Audible, or distribute one's own audiobooks and promote using a third party (free) audiobook player, or create one's own app for the appstore (but again, not where people look for audiobooks).
Audiobooks, Podcasts, and Spoken Word Music
In sum, audio books can be found in various formats in iTunes (and elsewhere), the technical format can be identical, but the metadata and where to find and what app to use to consume and manage audio books can differ significantly, as well as geographical restrictions. - Audio books are only available as spoken word music in Google Play, as well as suffering from geographical limitations (e.g., in Thailand Google Play Music simply doesn't exist) - Audio books as Audiobooks are available in iOS in iBooks (with geographical limitations) and as Audiobooks in iTunes for desktop (OSX, Windows) - and Apple uses Audible as the exclusive publisher of Audiobooks - Audio books as Spoken Word Music are available in iTunes (all platforms), and can be accessed through various third party aggregators, such as cdBaby, RouteNote, and Tunecore. - Audio books as Apps are available through various app stores, though one would need to build the app themselves. This is an interesting option, in that audio, text, and some kind of synchronization between the two could be useful (one could easily switch between reading text and having audio read). - Audio books as Video is more complicated as places like iTunes, Netflix, Amazon and the like are focused on TV and movie formats. Distribution on YouTube makes the most sense, but likely it is still best as a preview/trailer and free content to build leads for sales of other formats. - Podcasts are an older format but it is difficult to monetize on iTunes, as they are mostly and widely considered to be free. Podcasts are really more like radio, and radio is monetized through advertising. It is best to consider
Thailand actually has a pretty good option for both ebook, and more recently audiobooks, and that is Ookbee. This is for the Thai speaking marketplace only, but works well. For English-speaking markets, one can only rely on the fact that people would have accounts in non-Thailand markets for iTunes/iBooks and Android, or rely on Appstore apps (Music for Android and Audiobooks for iTunes are simply not available).