1 Corinthians 14:6-9 NIV

6 Now, brothers, if I come to you and speak in tongues, what good will I be to you, unless I bring you some revelation1 or knowledge2 or prophecy or word of instruction?3

References for 1 Corinthians 14:6

7 Even in the case of lifeless things that make sounds, such as the flute or harp, how will anyone know what tune is being played unless there is a distinction in the notes?
8 Again, if the trumpet does not sound a clear call, who will get ready for battle?4

References for 1 Corinthians 14:8

9 So it is with you. Unless you speak intelligible words with your tongue, how will anyone know what you are saying? You will just be speaking into the air.