I think that the visitors have been recording our communications for quite some time now and know how to speak to us. Most reports of human-alien encounters suggest that they have no problem speaking to us in our native language or projecting thoughts into our minds which we can respond to in the same way. It seems that in a typical classic abduction case the worker bee aliens (usually grays) do not speak or communicate but the leaders (often Nordics or otherwise non-Earthly humans) can speak just fine.