1 Corinthians 14:9-11

King James Version

⁹ So likewise ye, except ye utter by the tongue words easy to be understood, how shall it be known what is spoken? for ye shall speak into the air.

¹⁰ There are, it may be, so many kinds of voices in the world, and none of them is without signification.

¹¹ Therefore if I know not the meaning of the voice, I shall be unto him that speaketh a barbarian, and he that speaketh shall be a barbarian unto me.