in (the same) (Psalm 68:23), stringed instrument (Psalm 150:4), whereby (Psalm 45:8 (defective plural))

Concise Bible Dictionary:

There must have been with these prophets some knowledge of music, which doubtless under David was further cultivated and devoted to the service of God, their music being intimately connected with temple worship. He had several companies of singers, and players on instruments, which are often mentioned in the Psalm. As these were indited under the guidance of the Holy Spirit, we may conclude that this way of celebrating the praises of God was in accordance with the dispensation that then was. Such an exhortation as “Praise Him with the psaltery and harp,” is beautifully in place in the Psalms; but in the New Testament dispensation it is, “singing and making melody in your heart to the Lord”; and “I will sing with the spirit, and I will sing with the understanding also.” “They that worship Him must worship Him in spirit and in truth.”
In the headings of fifty-five of the Psalm the words occur, “To the chief musician”; the word is natsach, and simply means “to the chief or the leader,” and may therefore apply as much to the singers as to the musicians. The musical instruments are considered under their various names.

Strong’s Dictionary of Hebrew Words:

from an unused root meaning to apportion; a part; hence, a musical chord (as parted into strings)
KJV Usage:
in (the same) (Psalm 68:23), stringed instrument (Psalm 150:4), whereby (Psalm 45:8 (defective plural))