What tools and languages are useful to build and improve Intelligent Assistants?

Question

Like Siri, Viv, Amazon Echo, companion robots, etc.

Answer 1

Wit.ai is a service which provides a nice combination of both voice recognition and machine learning for developers. It provides the service to convert verbal commands into text and can also be trained up in how to understand those commands. 

https://www.sitepoint.com/five-simple-ways-to-build-artificial-intelligence-in-2016/

Answer 2

It's also possible via Android Studio to javascript, that's what I'm currently working on and it's coming out fine