Act 2:9
Parthians, and Medes, and Elamites, and the dwellers in Mesopotamia, and in Judaea, and Cappadocia, in Pontus, and Asia,
Act 2:10
Phrygia, and Pamphylia, in Egypt, and in the parts of Libya about Cyrene, and strangers of Rome, Jews and proselytes,
Act 2:11
Cretes and Arabians, we do hear them speak in our tongues the wonderful works of God.
Because we really do not know how many human languages 2:9-11 represents, people have proposed that the miracle was just in the HEARING...
Yet one group of disiples could have spoke to a Parthian group, others to an Arabian group, etc.
I wish we had a video of Acts 2, but we don't. I have heard it happenned on SOLOMON'S PORCH -- but I don't know.
Maybe Matthew was speaking Egyptian to a group of Egyptians gathered near him, maybe Phillip was speaking Parthian to a group of Parthians gathered near him, we really don't know exactly how it went down - other than disciples spoke in tongues they didn't know, and the hearers heard their own separate language.