What kinds of tongues were being spoken at Pentecost? Were any of them unknown (so-called "heavenly") languages?

            Acts 2:6 reads, “When this sound occurred, a crowd gathered and was in confusion, because each one heard them speaking in his own language.”[4] In the Greek, Strong’s number 1258, the word language is translated dialektos, διαλεκτος, which means conversation, speech, discourse, language, the tongue or language peculiar to any people.[5] These were not unknown “heavenly” languages. The Bible is clear; those that were filled with the Holy Spirit spoke in tongues, or languages, understandable to the crowd. Bock states, “They hear the message “in their own language” as the disciples speak to them in tongues.”[6]He goes on to say, “This direct communication bewilders or perplexes them.”[7]

This bewilderment comes from the idea that Galileans are uneducated and can’t possibly speak all these different languages; it is obviously the power of the Holy Spirit and clearly His filling the believers on the Day of Pentecost. There is an interesting parallel with the speaking in tongues issue on the Day of Pentecost and the Scripture regarding Babel – God confusing language, and here, God causing language to be understood. God is looking for all cultures to experience the gospel message of Jesus Christ. I like what an article I read states,

St. Luke's Pentecost story from the Acts of the Apostles, which puts the issue of the multiculturalism of the Gospel firmly before us with its reversal of the lower of Babel story and its resulting confusion of languages (Genesis 11:1-9) to the new reality of everyone hearing "them speaking in the native language of each" (Acts 2:6).[8]

It is our “new reality, ”e  God wants everyone everywhere to hear the gospel, and He wants it done where everyone gets it. 

[4] Holy Bible, New English Translation, Bible.org, Internet, available from https://net.bible.org/#!bible/Acts+2:5, accessed 18 July 2012.

[5] Thayer and Smith. "Greek Lexicon entry for Dialektos". "The KJV New Testament Greek Lexicon",  http://www.biblestudytools.com/lexicons/greek/kjv/dialektos.html (accessed 19 July 2012).

[6] Darrell L. Bock, Acts: Baker Exegetical Commentary On The New Testament (Michigan: Baker Academic, 2007), 100.

[7] Bock, 100

[8] "The Day of Pentecost May 27, 2012." Currents in Theology and Mission 39.1 (2012): 103+. Academic OneFile. Web. 20 July 2012.http://go.galegroup.com.ezproxy.liberty.edu:2048/ps/i.do?id=GALE%7CA280625507&v=2.1&u=vic_liberty&it=r&p=AONE&sw=w(accessed 19 July 2012).