The LSJ lexicon defines ψαλμός as "twitching or twanging with the fingers," "mostly of musical strings", "the sound of the cithara or harp," and "later, song sung to the harp, psalm."
It defines ψάλλω as "to touch sharply, to pluck, pull, twitch", "mostly of the strings of musical instruments, play a stringed instrument with the fingers, and not with the plectron", "sing to a harp", and "Pass., of the instrument, to be struck orplayed."
Occurrences of G5568 ψαλμός and G5567 ψάλλω:
1 Corinthians 14:26 How is it then, brethren? when ye come together, every one of you hath a psalm, hath a doctrine, hath a tongue, hath a revelation, hath an interpretation. Let all things be done unto edifying.
Ephesians 5:19 KJV Speaking to yourselves in psalms (ψαλμοίς) and hymns and spiritual songs, singing and making melody (ψάλλοντες) in your heart to the Lord;
The Apostolic Bible Polyglot translates ψάλλοντες as "strumming" in Ephesians 5:19.
"speaking to yourselves in psalms and hymns and spiritual odes; singing and strumming in your heart to the Lord;"
Colossians 3:16 Let the word of Christ dwell in you richly in all wisdom; teaching and admonishing one another in psalms and hymns and spiritual songs, singing with grace in your hearts to the Lord.
James 5:13 Is any among you afflicted? let him pray. Is any merry? let him sing psalms.(ψάλλω)
Since ψάλλω and ψαλμός is used to refer to instruments in the Septuagint, classical, and koine Greek as well as to singing with and without an instrument, does this indicate that the early Christians would have used musical instruments to accompany their singing?