Recent research has shown that people change the speed at which they speak to more closely match speech they have just heard. They don't imitate each other exactly, but they get sort of pulled in one direction or another, depending on whether a person speaks slowly or quickly.
Musicians are actually trained to match the tempos of others. Scientists say that while it makes sense that musicians adapt their tempos, being that they are trained to do so, it's not clear why speakers do it. After all, we don't have to speak at the same tempo in order to understand each other.
What's more is that when asked to repeat a sentence they heard from a recording, the subjects in this research inserted pauses in the same places where the recording they heard inserted pauses. They did this without being directed to mimic tempo or pauses.
In order to better understand these findings and to test them out in real interactions, scientists intend to study unscripted, casual conversation.