Dear Sir,
I'm C++/Qt programmer with 10+ years experience in the field.
In the past I did a similar program using C++ on windows, it uses google voice translator API.
I can do it for windows using Visual C++ or if you want to install it on different operating system then will use C++/Qt, it can be compiled for different platforms like: windows, linux, MAC, iOS or Android
Sincerely,
Nelucius