What is the most suitable dialog management solution for an oral English practice product?
Good question. I know of at least two companies working in this area: http://www.csiec.com and http://www.saybot.com Offhand, I am not aware of turnkey products to accomplish your goal. However, I recommend you look at the new Guile3D conversational agent (aka chatbot) Denise http://www.guile3d.com , basically taking advantage of Windows7 speech tools. I have asked Richard Wallace, inventor of AIML, a number of times for a list of known voice interactive applications, but so far without success. I have been told by Voxeo/Tropo that IVR Grammars are not up to this task, despite their announcement of partnering with http://artingence.com to do just this.
What caught my attention while listening to the paper you cited (in iPhone Web Reader text to speech app) was the mention of confidence scoring, of the type used in IBM Watson, and the use of Ngrams, such as Microsoft Web N-gram Services or Google Ngram Viewer.
