1)
What is "Asor"?
1.
Rashi: It is a harp of 10 strings. Malbim - this corresponds to the 10 Galgalim (spheres that house the Heavenly bodies; refer to 8:4:2:1). Nevel has eight strings, corresponding to the Galgal of the Mazalos and the seven below it.
2)
What is "Higayon"?
1.
Radak: It is a song said together with playing a harp.
