Adding voice control to OpenHAB + MQTT + ESP8266/Sonoff

Hello everyone,

I am not a programmer, and rather new to this kind of thing. But with enough googling, taking pieces of code, trial and error and watching a lot of youtube videos, I now have OpenHAB and MQTT working on a Pi3, and a couple of Sonoff devices connected to some lights. I have a couple of Android devices with the UI on them that I can tap to turn on and off the lights.

My next question is how to add voice commands to the project? I think it is possible since I saw some videos on youtube, but I don’t know how to. Any help would be great!