As someone mentioned - here we go again.
In answer to the question, I guess it depends on who you ask - here's a Linguist's take.....
There is absolutely nothing mysterious about Biblical "tongues" – when referring to something spoken, they are nothing more than real, rational language(s); usually unknown to those listening to them, but always known by the speaker(s) – it’s their native language (in some cases, it is a language the speaker has learned).
In contrast, the “tongues” Pentecostal and Charismatic Christians are producing today is an entirely self-created phenomenon. It is non-cognitive non-language utterance; random free vocalization based upon a subset of the existing underlying sounds (called phonemes) of the speaker’s native language, and any other language(s) the speaker may be familiar with or have had contact with.
It is, in part, typically characterized by repetitive syllables, plays on sound patterns, alliteration, assonance, and over-simplification of syllable structure. It is also interesting to note that any disallowed sound combinations, i.e. consonant clusters, in the speaker’s native language are also disallowed in his/her tongues-speech. Further, this subset of phonemes typically contains only those sounds which are easiest to produce physiologically.
There is absolutely nothing that “tongues-speakers” are producing that cannot easily be explained in linguistic terms.
Conversely, when it comes to something spoken, there are absolutely no Biblical references to “tongues” that do not refer to, and cannot be explained in light of, real rational language(s), though it may not be the explanation you want to hear, and it may be one which is radically different from what you believe, or were taught.
“Praying in the Spirit” does not refer to the words one is saying. Rather, it refers to how one is praying. In the three places it is used (Corinthians, Ephesians, and Jude), there is absolutely zero reference to 'languages' in connection with this phrase. “Praying in the Spirit” should be understood as praying in the power of the Spirit, by the leading of the Spirit, and according to His will. In Pentecostal/Charismatic parlance however, the phase has come to be equated with modern “tongues”, i.e. when one “prays in the Spirit”, one is typically engaged in some form of tongues-speech.
The word “tongue(s)” itself is simply a more archaic word for (real) “language(s)”, nothing more. Replace “tongue(s)” with “language(s)” in these various passages and the whole modern Pentecostal/Charismatic concept of “tongues” begins to become difficult to posit – “language(s)” sounds a lot less mysterious, and in many cases, adds more clarity to the text. Again, in Pentecostal/Charismatic parlance however, the word has come to be equated with the modern concept of “tongues-speech”.
Most people who use ‘tongues’ are very keen on describing the ‘experience’. Indeed, for those that use it, it is very psychologically, physically, and spiritually fulfilling. It’s almost like primal screaming. When people practice ‘tongues’, they feel a sense of sweet release and inner peace, in that virtually all stress can be gone after the experience.
People describe the experience, but in examining the “mechanics” behind it…well, not so much. When a person has experienced tongues, s/he is absolutely convinced as to the ‘scripturalness’ of his/her experience, and the correctness of his/her doctrinal beliefs – this, despite the overwhelming scriptural absence of anything remotely akin to what they’re doing.
I'm not doubting or questioning the 'experience'; as mentioned, glossolalia as the spiritual tool that it is, can be very powerful and, for many people, the experience is profound. Both the spiritual and physical benefits of using this tool are also well documented. Again though, it is important to note that this same statement can be made for virtually _any other culture that practices glossolalia_ . Religious and cultural differences aside, the glossolalia an Evenki Shaman in Siberia, a vodoun priestess in Togo and a Christian tongues-speaker in Alabama are producing are in no way different from each other. They’re all producing their glossolalia in the exact same way; they just have different explanations and beliefs as to why they’re doing it and where it comes from.
“Tongues” is to some Christian believers a very real and spiritually meaningful experience but consisting of emotional release via non-linguistic ‘free vocalizations’ at best; non-cognitive non language utterance – the subconscious playing with sounds to create what is perceived and interpreted as actual, meaningful speech. In some cases, I would argue that it is clearly a self/mass delusion prompted by such a strong desire to “experience God” that one creates that experience via “tongues”.
Known by many different names, “tongues”, “glossolalia”, or more accurately “non-cognitive non-language utterance” (NC-NLU), is practiced by many cultures and religious beliefs from literally all over the world; it is relatively new to Christianity and certainly not unique to it.
As a point of note, I’m a Linguist, and let me also add here that I am neither a so-called ‘cessationist’ nor a ‘continuationist’ – I do not identify with either term; in fact, I had never heard the two terms until just late in 2016. As far as I’m concerned, quite frankly, since the Biblical reference of “tongues” is to real, rational languages, obviously “tongues” haven’t “ceased”; people still speak.