We are expected to talk between partners especially from senior to junior. It's my sensei's perspective to allow the seniors to help the juniors. That senior can be a 4th kyu working with a newbie or the senior can be the 1st kyu working with the 4th kyu or they can be the nidan working with the 1st kyu.
The coversation is also expected to go the other way especially so the junior can communicate to the senior to take it down a notch. I find myself doing that a lot. I'm 4th kyu which means I'm getting more comfortable with my ukemi but I'm not so comfortable that one of my senior's (shodans) can still get a full workout like they could with a fellow shodan or 1st kyu. What happens is that we start at a slower pace work up then I hit a point where my ukemi is too slow for their skill. I just say so and they have no problem with taking it down a notch. I also like pushing myself a little so I won't say so until I really feel like I need to back down a little.
But I'm not talking full fledged conversations here. But really just approval of people speaking enough on the mat so people can help each other improve. As long as people don't over coach it's okay. I usually don't see a lot of that on the mat even with an open attitude so most people focus on training. Sensei also keeps a watchful eye and usually steps in if someone takes it too far.