William Burkitt on 1 Corinthians 14:7

Our apostle here proceeds to illustrate his former arguments by a similitude taken from musical instruments, the one used in peace, to wit, the harp; the other in war, to wit, the trumpet; as they are useless, if by distinction their signification is not perceived; for if a man hears not, or understands not, the sound of the harp or trumpet, he cannot prepare himself either for the dance, or the battle: so if persons in the church do not speak intelligibly, they will nothing edify: it is like beating the air, all is vain and to no purpose.