Perhaps you have conflated two distinct performances.
The gift portrayed in Acts 2:4 and following is the ability to speak in other natural languages so as to be understood by native speakers of those languages who are present at the time of the mysterious utterance. Acts continues from 2:5 through 2:11
The "interpreters," then, are the listeners themselves.Now there were dwelling in Jerusalem Jews, devout men, from every nation under the sky. When this sound was heard, the multitude came together and were bewildered, because everyone heard them speaking in his own language. They were all amazed and marveled, saying to one another, “Behold, aren’t all these who speak Galileans? How do we hear, everyone in our own native language? Parthians, Medes, Elamites, and people from Mesopotamia, Judea, Cappadocia, Pontus, Asia, Phrygia, Pamphylia, Egypt, the parts of Libya around Cyrene, visitors from Rome, both Jews and proselytes, Cretans and Arabians—we hear them speaking in our languages the mighty works of God!”
In contrast, Paul appears to be describing glossolalia, or the mimickry of connected speech sounds for which there is no natural language in which these sounds are coherent utterances (or, at least there are no native speakers of any such language among those present). In such circumstances, that there is a role for somebody to say something intelligible to the audience is obvious.
John Belushi and Richard Pryor demonstrate what Paul was talking about:
Chevy Chase portrays the Acts miracle, understanding Belushi and Pryor as if they were speaking English, Chase's native language.