1 Corinthians 14:7-9

King James Version

⁷ And even things without life giving sound, whether pipe or harp, except they give a distinction in the sounds, how shall it be known what is piped or harped?

⁸ For if the trumpet give an uncertain sound, who shall prepare himself to the battle?

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.