What Acts chapter 2 records more specifically is a re-presentation of the gift of the Torah on Mt. Sinai as found in Exodus 19. After the fall of the temple of Jerusalem in 70 C.E., the Feast of Weeks (pentekoste hemera in the Greek of LXX Tobit 2:1 and 2 Macc. 12:32) became a celebration of the giving of the Torah. Note carefully the connections Luke makes with that earlier Torah gift. Fire is often connected with the Torah itself in early Jewish literature. Philo quite explicitly connects the communication of speech with flame in his On the Decalogue. Luke regularly connects Jesus and Moses in his telling of the story. Hence, the use of sound and fire here in Acts 2 must remind us of the Sinai gift of Torah. At Acts 2:33 Peter speaks of "receiving the promise of the Spirit" and having that Spirit "poured out" as the Jews are witnessing this day. Likewise, Stephen at Acts 7:38 speaks of how Moses "received living words to give to us." Just as Moses received Torah from YHWH on Sinai, so now Jews are again receiving a spiritual Torah from God through God's greatest deed of the gift of Jesus Messiah.
What Pentecost proclaims is the transforming power of the Holy Spirit in the same way that YHWH's Torah was given as transforming gift to make Israel into God's covenant people. Pentecost is then not about pyrotechnics and the magic of multiple languages pouring from the mouths of Galilean peasants. It is about hearing the "great deeds of God" so clearly and so powerfully that our lives are transformed into followers of the Prince of Peace, the one who calls us forth to be doers of justice in the face of injustice, to be purveyors of peace in a world of violence.
May your Pentecost celebration this year be one of transforming power for you and for those who are witnesses.