Were The Tongues Spoken In The Bible Existing Languages?

A standard of biblical interpretation is that we use scripture to define and refine scripture.  Often when a word or concept is first introduced in the Bible, a definition of it follows close by.  Using this approach to studying and interpreting scripture, would we understand the tongues spoken in the New Testament to be existing, literal languages or unknown languages new to the speaker and the listener?  In this podcast, we explore the verses related to the topic to draw our conclusion.