Maybe this will help:
"For one who speaks in a tongue does not speak to men but to God; for no one understands, but in his spirit he speaks mysteries...One who speaks in a tongue edifies himself; but one who prophesies edifies the church... So also you, unless you utter by the tongue speech that is clear, how will it be known what is spoken? For you will be speaking into the air.
There are, perhaps, a great many kinds of languages in the world, and no kind is without meaning.
If then I do not know the meaning of the language, I will be to the one who speaks a barbarian, and the one who speaks will be a barbarian to me.
So also you, since you are zealous of spiritual gifts, seek to abound for the edification of the church.
Therefore let one who speaks in a tongue pray that he may interpret.
For if I pray in a tongue, my spirit prays, but my mind is unfruitful.
What is the outcome then? I will pray with the spirit and I will pray with the mind also; I will sing with the spirit and I will sing with the mind also.
Otherwise if you bless in the spirit only, how will the one who fills the place of the ungifted say the "Amen" at your giving of thanks, since he does not know what you are saying?
For you are giving thanks well enough, but the other person is not edified.
In the Law it is written, "BY MEN OF STRANGE TONGUES AND BY THE LIPS OF STRANGERS I WILL SPEAK TO THIS PEOPLE, AND EVEN SO THEY WILL NOT LISTEN TO ME," says the Lord. So then tongues are for a sign, not to those who believe but to unbelievers; but prophecy is for a sign, not to unbelievers but to those who believe.
Therefore if the whole church assembles together and all speak in tongues, and ungifted men or unbelievers enter, will they not say that you are mad?
But if all prophesy, and an unbeliever or an ungifted man enters, he is convicted by all, he is called to account by all;
If anyone speaks in a tongue, it should be by two or at the most three, and each in turn, and one must interpret;
but if there is no interpreter, he must keep silent in the church; and let him speak to himself and to God.
This is all from 1 Cor 14.