You are mistaken. "Conversation" in the KJV does not mean a verbal exchange; it signifies one's lifestyle or manner of life.
Conversation
Generally the goings out and in of social intercourse (Eph. 2:3; "4:22; R.V., "manner of life"); one's deportment or course of" life. This word is never used in Scripture in the sense of verbal communication from one to another (Ps. 50:23; Heb. 13:5). "In Phil. 1:27 and 3:20, a different Greek word is used. It there" "means one's relations to a community as a citizen, i.e.," citizenship.
The Greek word
anastrophe signifies "way of life, conduct, behavior" (Shorter Lexicon of the NT, 14).
The text thus specifies that God commands holiness in all of our conduct and behavior. You have to prove that what believers do with instrumental music is an exception to the command.