The greatest aid to this practice of keeping God in memory is, perhaps, music. The Lord says to Nârada, the great teacher of Bhakti, "I do not live in heaven, nor do I live in the heart of the Yogi, but where My devotees sing My praise, there am I". Music has such tremendous power over the human mind; it brings it to concentration in a moment. You will find the dull, ignorant, low, brute-like human beings, who never steady their mind for a moment at other times, when they hear attractive music, immediately become charmed and concentrated. Even the minds of animals, such as dogs, lions, cats, and serpents, become charmed with music.
The Complete Works of Swami Vivekananda/Volume 4/Addresses on Bhakti-Yoga/The Preparation