No, I haven’t done that. It’s not too hard to do it though. If your robot is based on something like a Raspberry Pi (a tiny computer) then you can easily install some speech synthesizer software on it to let it deliver spoken messages. Making a robot that can hold a back-and-forth conversation with a person is much more difficult though because the robot needs to be able to understand language, rather than just producing speech sounds. I have a PhD student who’s working on algorithms to analyse speech signals, so I do some work in that area, but it’s not currently linked to my robotics work.