Question about "speaking in tongues"

[The Matt]

I've a few questions about tongues. (the initial evidence, and praying in tongues) How does one know it is real? (not others know, how does the speaker know?) What should one feel? Can you stop yourself from speaking them? When I was in church before, I was young and just wanted to be doing it like everyone else, so I copied parts of other peoples tongues and blended them together. I'm older now and taking it a lot more seriously, and I just want to be sure it's legitimate this time. I want to make this clear, I don't doubt it's real, I just don't want to make a mistake.