Answer: Baal HaSulam’s group consisted of less than ten people, and everyone came from different places. Each had their own melodies that they played at mealtimes or during prayers, especially on the Day of Atonement (Yom Kippur).
So Baal HaSulam composed his own melodies, and taught the students not to sing foreign prayers to the words from the prayer book. That is how the melodies to the texts of Ari and “Bnei Eihal” came out, “Kel Mistater,” etc.
Question: Can these melodies and their text somehow affect a person listening to them?
Answer: They do possess certain spiritual forces. A melody has a great power, but it can only be attained to the degree that a person is dwelling in it.
From the Kabbalah Lesson in Russian 10/16/16