Some clues I have picked up about these Denisovans
The lived in high, cold places, eschewing warm, temperate, forest or plains to live because they were the ultimate environmentalists, as we would call them today, not wanting to harm animals, plants, fish by living among them. Their language, like Neanderthals, was tonal, rather than word-using like other species because of where their larynx were situated in their throats - giving their speech high-pitched soprano like sounds.
My 2 cents
The myth of how the Neandertal spoke (or couldn’t speak) is long gone.
https://www.bbc.com/news/science-environment-25465102