Murmur
Srimad-Bhagavatam
SB Canto 4
SB 4.8.54, Purport:
The prescribed rules, as stated here by Nārada Muni, are that one should accept the mantra through a bona fide spiritual master and hear the mantra in the right ear. Not only should one chant or murmur the mantra, but in front of him he must have the Deity, or physical form of the Lord. Of course, when the Lord appears it is no longer a physical form. For example, when an iron rod is made red-hot in a fire, it is no longer iron; it is fire. Similarly, when we make a form of the Lord—whether of wood or stone or metal or jewels or paint, or even a form within the mind—it is a bona fide, spiritual, transcendental form of the Lord.