From “
Lumen Gentium” The Dogmatic Constitution of the Church
(note the title “Dogmatic”. the content are therefore deemed infallible as they are an act of the Ordinary Magisterium of the Church acting together (in an eccumenical council) and intending to make a definitive and binding declaration).
from Para 4
The Church, which the Spirit guides in way of all truth(15) and which He unified in communion and in works of ministry, He both equips and directs with hierarchical and charismatic gifts and adorns with His fruits.(16) By the power of the Gospel He makes the Church keep the freshness of youth. Uninterruptedly He renews it and leads it to perfect union with its Spouse. (3*) The Spirit and the Bride both say to Jesus, the Lord, “Come!”(17)
From Para 12
It is not only through the sacraments and the ministries of the Church that the Holy Spirit sanctifies and leads the people of God and enriches it with virtues, but, "allotting his gifts to everyone according as He wills,(114) He distributes special graces among the faithful of every rank. By these gifts He makes them fit and ready to undertake the various tasks and offices which contribute toward the renewal and building up of the Church, according to the words of the Apostle: “The manifestation of the Spirit is given to everyone for profit”.(115) These charisms, whether they be the more outstanding or the more simple and widely diffused, are to be received with thanksgiving and consolation for they are perfectly suited to and useful for the needs of the Church. Extraordinary gifts are not to be sought after, nor are the fruits of apostolic labor to be presumptuously expected from their use; but judgment as to their genuinity and proper use belongs to those who are appointed leaders in the Church, to whose special competence it belongs, not indeed to extinguish the Spirit, but to test all things and hold fast to that which is good.
The above is official, the following is my understanding:
In keeping with the Scriptural accounts of “Tongues” and its existence in “various forms”, it is clear to my understanding that the Gift of Tongues, as a supernatural spiritual gift, may take a number of forms.
- Glossolalia. As mentioned above by others, when subject to objective scrutiny any claims that the speaker is “praying in another language, either currently or long dead” does not withstand analysis. Rather this is a time when inspired by the spirit the person praying allows the movement of the spirit within them to pray with “deep groans and sighs” which does not require the verbal mind to express. Such experiences are described in various ways by many of our sainted mystics.
- Miraculous speech or prayer in a language the speaker does not and could not possibbly know, by which a prophetic message is delivered to a listener who does speak that language. (note this is not what is described in Acts… I’ll come to that). This is a manifestation that has been described repeatedly - especially in missionary contexts by missionaries or by those ministering to others in desperate need of evidence Gods Presence. Just because this happens occasionally does not mean that the majority of Glossolalia falls within this category.
- Glossolalia with interpretation by another. This is different from 2). here one person prays aloud in Glossolalia during a time of public or group worship, and one or more other persons present receive a prophetic understanding from the Holy Spirit as an Interpretation of the Glossolalia.
Understanding of Tongues.
This can occur in at least 2 ways:
a) the interpreter(s) described in 3) above.
b) As described in the description of Penticost in Acts, the Apostles spoke aloud to the assembled people from many countries and each person heard and understood the speech in his own language. - As there is just 1 or a few speakers, but many listeners hearing in their own languages, then the miracle here is one of “Interpretation” not “Tongues”.
c) as a subset of b) the situation in 2) above may be a gift of miraculous interpretation to the listener just as easily as a gift of miraculous tongues in the speaker.