1 Corinthians 14:7-9

7Yet even lifeless things, either flute or harp, in producing a sound, if they do not produce a distinction in the tones, how will it be known what is played on the flute or on the harp?

8For if 1the 2bugle produces an indistinct sound, who will prepare himself for battle?

9So also you, unless you utter by the tongue speech that is clear, how will it be known what is spoken? For you will be 3speaking into the air.