Acts 2:8

And how hear we, every man in our own language wherein we were born? Parthians and Medes and Elamites, and the dwellers in Mesopotamia, in Judaea and Cappadocia, in Pontus and Asia, in Phrygia and Pamphylia, in Egypt and parts of Libya about Cyrene, and sojourners from Rome, both Jews and proselytes, Cretans and Arabians, we hear them speaking in our own tongues the mighty works of God. And they were all amazed, and were perplexed, saying one to another, What meaneth this? But others mocking said, They are filled with new wine.

This list of geographical names shows the diversity of the people to whom the apostles spoke, the provinces and locations mentioned lying in all directions from Jerusalem and representing a cross-section of the languages spoken in the entire Roman empire. As stated above, it is a mistake to suppose all of these languages were spoken "at once" and by a single speaker. Such a supposition would embellish this wonder far beyond the text. As Walker said:

It is probable that each of the eleven addressed the multitude in a different language. People would naturally gather around the man using their native language. We may thus imagine eleven congregations assembled within the same large area, all listening to the same sermon, in substance at least, but each in his own language.[20]

Root also concurred in this view, saying:

It is not necessary to assume that each visitor heard the sermon of Peter in his own tongue; but, in the beginning of the morning's meeting, the various languages were spoken by the apostles.[21]

The wonder of some and the mockery of others sprang from the sensational event of the Twelve apostles (this student believes Matthias participated in this) preaching all at one time to twelve assemblies at various places in the large temple enclosure. The power and eloquence of men who but a short while previously had been fishermen in Galilee was an astounding thing; and the scoffers could think of no better explanation than to charge them with drunkenness, a charge as unreasonable as it was malicious. Peter would dispose of that slander in a brief word a little later.

[20] W. R. Walker, Studies in Acts (Joplin, Missouri: College Press, n.d.), p. 17.

[21] Orin Root, Commentary on Acts (Cincinnati, Ohio: Standard Publishing Company, 1966), p. 10.