Acts 2:1-13 recounts the arrival of the Holy Spirit with special emphasis placed on the disciples speaking in foreign tongues. There is some level of dispute as to whether each tongue was actually known or whether there were so called “heavenly tongues” added to the mix.
First to consider is Acts 2:5-8 which states: “Now there were staying in Jerusalem God-fearing Jews from every nation under heaven. When they heard this sound, a crowd came together in bewilderment, because each one heard their own language being spoken. Utterly amazed, they asked: ‘Aren’t all these who are speaking Galileans? Then how is it that each of us hears them in our native language?”
This passage begins by stating that there were Jews representative of every nation under heaven. As it moves, it states that each person heard their own language spoken. This leaves no doubt in my mind that each language was identifiable. The number of disciples present clearly makes the case for they varying number of languages that were spoken. Besides this, the various cultures are listed who received the revelation. They are “Parthians, Medes and Elamites; residents of Mesopotamia, Judea and Cappadocia, Pontus and Asia,Phrygia and Pamphylia, Egypt and the parts of Libya near Cyrene; visitors from Rome (both Jews and converts to Judaism); Cretans and Arabs.” Here Luke confirms that the tongues were not only established languages, but they were identifiable by the various cultures present.
Gary Burge and Andrew Hill provide a sound addition to my assessment as they contend that the tongues were “intelligible to different parts of the Roman world (c.f. 2:8)” In the opinion of this writer, God would have no use for using tongues of a heavenly nature here as He is seeking to proclaim His message to all cultures present through the disciples. God does not waste His revelations and surely wanted to reach the hearts of all men present.
Where I could see someone making the case for “heavenly tongues” is when some in the crowd mocked the disciples and asserted they may have been drunk. However, not everyone who hears the Gospel responds positively. It can be said that a majority of these people were living when Jesus was crucified and were sure He was dead. It would take either a crazy person (or a drunk) to assert that the dead was now alive. Or it would take an act of God to bring someone back from the dead, let alone bestow the power to preach across the globe. The fact that some people could not understand the tongues of nations other than their own may have caused them to dismiss those tongues as drunken slurring.
 Acts 2:5
 Acts 2:6, Acts 2:8
 Acts 2:9-11
 Burge, Gary M. and Hill, Andrew E. p. 1172.
 Acts 2:13
 Bock, p. 105.