Understanding speaking in tongues

When the Day of Pentecost had fully come, they were all with one accord in one place.  2  And suddenly there came a sound from heaven, as of a rushing mighty wind, and it filled the whole house where they were sitting.  3  Then there appeared to them divided tongues, as of fire, and one sat upon each of them.  4  And they were all filled with the Holy Spirit and began to speak with other tongues, as the Spirit gave them utterance.  5  And there were dwelling in Jerusalem Jews, devout men, from every nation under heaven.  6  And when this sound occurred, the multitude came together, and were confused, because everyone heard them speak in his own language.  7  Then they were all amazed and marveled, saying to one another, "Look, are not all these who speak Galileans?  8  And how is it that we hear, each in our own language in which we were born?  9  Parthians and Medes and Elamites, those dwelling in Mesopotamia, Judea and Cappadocia, Pontus and Asia,  10  Phrygia and Pamphylia, Egypt and the parts of Libya adjoining Cyrene, visitors from Rome, both Jews and proselytes,  11  Cretans and Arabs—we hear them speaking in our own tongues the wonderful works of God."
Acts 2:1-11

Four simple observations on this lengthy passage:

First, everything in Acts is correctly recorded. However, not everything recorded in Acts is “normative” for all Christians everywhere at all times. This is true because Acts is a record of a special transitional time. This first point is important to remember when reading anything in Acts. We can consider events in Acts as normative only if they are also written about in the rest of the New Testament that is didactic [doctrinal teaching]. Remember the danger of basing doctrine on narratives, unless the doctrine is also taught as doctrine elsewhere in the Bible.

Second, speaking in tongues is not normative. If it were, it would be taught in the epistles that all Christians must speak in tongues. Not only is that idea not taught, the opposite is taught in 1 Corinthians 12:7-12, & 28-31.

Third, verses 8 & 11 say that the tongues were in known languages understood by those present. The reason for these tongues was to give understanding about God to people present who speak a language different from the native tongue of the one speaking. Speaking in tongues is not a “heavenly prayer language” that no one understands.

Fourth, verse 11 says that the subject matter of what was spoken in tongues was “the wonderful works of God.” In other words, praises to God for His goodness. There is nothing in scripture that teaches that God gives special messages to people who all speak the same language through one speaking in tongues, which is then understood only when an interpretation is given. What would be the sense in that?