I've been on a blog hiatus but now I'm back to business.
If you have gotten the vowelviz app great, if you haven't you should consider it.
Watch the demos. It's like getting a mini vowel lessons while you learn the app. The vowelviz app is primarily for vowels across the linguistic hierarchy. It's great for vowels, diphthongs, and many vocalic /r/ words, phrases and sentences.
http://www.completespeech.com/speech/site/
https://itunes.apple.com/us/app/vowelviz/id740035896?mt=8