All the examples of 'speaking in tongues' that I have heard are, in my opinion, examples of speaking gibberish without any sign that the Holy Spirit is at work.
i hear that a lot but ya know ... i also hear people of many nations speaking other languages and they sound like gibberish to me also .I think we must remember that just because we do not understand the words a person is speaking praying or singing .. and it "sounds like" gibberish .. does not mean it is gibberish . it only means we cannot understand it .
so we must be careful how we speak about it . a man from, say Bangladesh, could stand beside you and speak quickly to you in his own tongue and we could say go away you annoying person .. only to find he was a christian and was trying to explain the gospel to us .. and we mocked him.
of course that can happen via misunderstanding .. but the truth is it can only happen when we base our judgment of the event on the outer appearance . and nothing to do with the lord is about the outer appearance ..it all begins in the heart and is seen by god in the heart for he looks upon the heart of man .
so we cannot be so swift to make judgment of tongues based on the outer sound our outer ears hear .
it is a spiritual language .. there are over 2000 major languages and how many dialects on the earth ? if the natural tongues of man are so varied -how much more so the language of the holy Spirit.
having said that i have also observed outwardly ...I do have ears haha . that at times the differing tongues i speak in are as distinctly different as English is from Swahili .i know when i am praying for the lost it is one tongue and when i am praying in spiritual warfare it is another tongue etc ..
of course some will ask how do you know what you are praying for ..? i don't always but often the lord shows that to me .after all i also asked him for the gift of interpretation f tongues and discernment of Spirits and word of Knowledge and gift of healing etc .. After all it is written to earnestly desire (covet) ALL the gifts .. so i Do, i ask and i receive,. after all if we do not believe that we will recive what we ask the lord for .. then we have no place praying to him .