Severian of Gabala

"There are doubtless many different languages in the world, and none is without meaning." 1 Cor 14:10
"There is no language without meaning because all languages are human." (ACCS, 139)
This comment strongly conveys his belief that any gift of tongues is "xenolalia" and not "glossolalia."

"Thus, tongues are a sign not for believers but for unbelievers, while prophecy is not for believers but for unbelievers." 1 Cor 14:22
"Clearly tongues are beneficial when the listener realizes that the one who speaks in tongues is using a language he does not know, one that has no human source. But the content of what is said does not help the hearer because he does not understand it." (CB, 234)
When Severian of Gabals refers to the language as not having a human source, he would refer to it in the sense of efficient causality. In other words, the speaking of the language does not have a human cause, because the individual did not study and learn it as others who spoke that language did. It is a comment on the learning of the language and not the language itself. The language is human while the mode of learning is divine.

"If any speak in a tongue, let there be only two or at most three, and each in turn; and let one interpret. But if there is no one to interpret, let each of them keep silence in church and speak to himself and to God." 1 Cor 14:27-28
"When Paul says let him keep silent, he teaches that a person who is speaking in the Holy Spirit speaks when he wishes and is silent when he wishes. This is the practice of the prophets, but not of those possessed by an unclean spirit. The latter speak when they do not wish and utter thing they do not understand." (CB, 237)
Obviously, the individual with the gift of tongues exercises control over this gift. This seems to lend even more credibility to the reading of "tongues" as "xenolalia" as opposed to the spontaneous and uninterpretable "glossolalia."