Acts 2:8

They spoke with strange tongues, and not those of their native land; and the wonder was great, a language spoken by those who had not learnt it. And the sign is to them that believe not, and not to them that believe, that it may be an accusation of the unbelievers, as it is written, With other tongues and other lips will I speak unto this people, and not even so will they listen to Me saith the Lord. But they heard. Here stop a little and raise a question, how you are to divide the words. For the expression has an ambiguity, which is to be determined by the punctuation. Did they each hear in their own dialect so that if I may so say, one sound was uttered, but many were heard; the air being thus beaten and, so to speak, sounds being produced more clear than the original sound; or are we to put the stop after "they Heard," and then to add "them speaking in their own languages" to what follows, so that it would be speaking in languages their own to the hearers, which would be foreign to the speakers? I prefer to put it this latter way; for on the other plan the miracle would be rather of the hearers than of the speakers; whereas in this it would be on the speakers' side; and it was they who were reproached for drunkenness, evidently because they by the Spirit wrought a miracle in the matter of the tongues.

Long after the old ark had overcome the waters of the sea, malicious people wished to extend their tower [of Babel] into heaven. In them, irreligious hearts divided the forms of their speech, and the good will in these arrogant confederates perished with their voice. At that time there was a confusion of language for a homogenous race; now there is one [language] for many since [that language] rejoices at the appearance of the coming church, [a language that] will have harmonious sounds; and [the church] brings about a return of eloquence in peace for the obedient [apostles], and the humble order gathers again what arrogant people scattered.

The multitude was perplexed or disturbed, for reasonably they supposed that wondrous things were being shown to them, on account of the bold deeds done concerning Christ, and conscience troubled their souls. And some were murderous in this way; but the devout ones were amazed, recognizing them as Galileans yet hearing them speak in their native tongues.

But the apostles knew what they were saying, namely the mighty works of God; as for the languages, they did not know them, except that the men who heard were devout, for example some Scythian by chance, or an Indian who understood the Scythian, or that the apostles spoke in the dialect of the Indians.