A bit over twenty or thirty years ago a couple of young Greek women brought a friend of theirs, a young French woman, to see Elder Porphyrios. Initially both Greek women stayed in the room with her, one of them translating the French woman's questions into Greek and the Elder's answers into French. After a little while though, Elder Porphyrios sent the woman who was translating out of the room while allowing the other, who didn't speak French, to remain a little longer. For the time that she remained in the room she heard the woman speaking in French and Elder Porphyrios responding in Greek. After that, the Elder sent her too out of the room and spoke with the French woman alone. When she finally came out she scolded her friends for having told her that the Elder could not speak French, since from the time the first woman had been sent out, Elder Porphyrios had spoken to her in fluent French. The second woman however was witness to the fact that Elder Porphyrios had spoken only in Greek the whole time she was in there. Elder Porphyrios explained later to the two women that while the French woman spoke only in French, he heard all her responses in Greek.
I believe this is what the gift of speaking in tongues entails, with the Holy Spirit enabling both parties, the speakers and the hearers. I suspect that if only one half of the equation is there, ie. if there are no "hearers" included in the gifting, that the "gift" may indeed be suspect, hence Pauls exhortation that if no one is there to interpret then those speaking in tongues should be silent.