They "began to speak with other languages" (2:4). What were the languages?

Acts tells what happened and what the hearers said, and no more. "They were all filled with the Holy Spirit and began to speak with other languages, as the Spirit gave them the ability to speak." (2:4). The multitude "were bewildered, because everyone heard them speaking in his own language" (2:6). They said, "How do we hear, everyone in our own native language?" (2:8), named peoples and places (2:9-11), and said, "we hear them speaking in our languages the mighty works of God!" (2:11). Others, mocking, said, "They are filled with new wine." (2:13). Acts tells of speaking with other languages again in later chapters (10:46, 19:6), each in its own words. The chapter says nothing more about the languages of 2:4 than these verses, and these notes don't either.