Speaking in Tongues in Scripture:
There are two kinds:
One type is mentioned in 4 verses of Acts Chapter 2: verse 4,6,8,11: "They begun to speak other languages, as the Spirit enabled them to speak;" "the crowd was exited because each heard them speaking in his own native language", and the disciples were all Galilean!
Most people would say that the great miracle of Pentecost has never happened again in the Church, or has it? The language of "joy" is understood by anybody. If you love someone, he or she will understand you, no matter what language is spoken, even if it is German or Russian or Chinese or Japanese. The languages of "joy", and "love", and "peace", are understood by everyone, and they are probably the greatest miracles of of all times.
The other kind of speaking in tongues is one of the 9 gifts of the Spirit mentioned three times in 1Cor.12:10,28,30, and explained again in 1Cor.14:1-33, where the gift to "speak in tongues" or "praying in tongues" is mentioned 12 times. It is the only one of the 9 gifts of the Spirit given "to strengthen us personally, as an individual", and we all need to strengthen ourselves at all times! (1Cor.14:4)
All the other 8 charismatic gifts are for service, to strengthen the Church (1Cor.12:7).
St. Paul talks about the Charismatic gifts in the First Letter to the Corinthians Chapters 12 and 14, but in between them, in Chapter 13, he proclaims "love" as the greatest gift, a language that anybody can understand, and without it, all the other gifts are worthless.