Albert Barnes Commentary 1 Corinthians 14:11

"If then I know not the meaning of the voice, I shall be to him that speaketh a barbarian, and he that speaketh will be a barbarian unto me." — 1 Corinthians 14:11 (ASV)

The meaning of the voice. Of the language that is uttered, or the sounds that are made.

I will be to him, etc. What I say will be unintelligible to him, and what he says will be unintelligible to me. We cannot understand one another any more than people can who speak different languages.

A barbarian. See Barnes on Romans 1:14.

The word means one who speaks a different or a foreign language.