The real research is understanding how this is tracked by neural populations - the article says researchers found a sort of buffer system that can keep track of three phonetic sounds at a time in order. It looks like rather than a separate encoding for time stamps, the neural populations fire in sequence, so the signals in the buffer propagate through populations (at least that’s what I understood). It’s not so surprising that this happens, but it is interesting that these scientists seem to have worked out some of the detailed mechanisms of how it happens.