I've been doing some research on the feasibility of building a mobile/web app that allows users to say a phrase and detects the accent of the user (Boston, New York, Canadian, etc.). There will be about 5 to 10 predefined phrases that a user can say. I'm familiar with some of the Speech to Text API's that are available (Nuance, Bing, Google, etc.) but none seem to offer this additional functionality. The closest examples that I've found are Google Now or Microsoft's Speaker Recognition API:
http://www.androidauthority.com/google-now-accents-515684/
https://www.microsoft.com/cognitive-services/en-us/speaker-recognition-api
Because there are going to be 5-10 predefined phrases I'm thinking of using a machine learning software like Tensorflow or Wekinator. I'd have initial audio created in each accent to use as the initial data. Before I dig deeper into this path I just wanted to get some feedback on this approach or if there are better approaches out there. Let me know if I need to clarify anything.
You could use(this is just an idea, you will need to experiment a lot) a neural network with as many outputs as possible accents you have with a softmax output layer and cross entropy cost function