Anthropologists and computer geeks have worked their magic and reproduced Neanderthal speech. Yes, they spoke. They just didn’t sound anything like modern humans.
The conclusion is that Neanderthals spoke, but sounded rather different to us. Specifically, the ancient humans’ lacked the “quantal vowel” sounds that underlie modern speech and which provide cues that help speakers understand one another.
By modeling the sounds that a Neanderthal larynx would have made, McCarthy’s team engineered the sound of a Neanderthal saying “e.”
In contrast to a modern human “e,” the Neanderthal version lacks a quantal hallmark, which helps a listener distinguish the word “beat” from “bit,” for instance.