In the material world, we experience how much influence sound vibration has on our consciousness. A particular song can make us sad or happy, an alarm can invoke fear, and the sound of someone's voice can bring comfort. If mundane sound vibrations can so profoundly affect our temporary state of mind, we can only begin to imagine the power of transcendental sound vibration.
Srila Prabhupada often explained that there is a vast difference between material sound and spiritual sound (śabda-brahman). Material sound is localized and temporary; it deals with the affairs of the physical body and the temporary world. Spiritual sound, however, descends directly from the spiritual platform and is non-different from the Absolute Truth itself.
The Hare Krishna mahāmantra is a transcendental sound vibration that originates in the spiritual world (Goloka Vrindavana). When we chant it, we are not producing a material noise but are receiving and transmitting a spiritual frequency. Just as one might tune a radio to a specific frequency to catch a broadcast from far away, by chanting Hare Krishna, the soul tunes its consciousness to the spiritual realm.
Because the holy name is fully spiritual, it instantly cuts through the coverings of the material mind and intelligence, touching the soul directly. Sound is the subtlest material element (ether), and transcendental sound is the medium through which the spiritual world interacts with the material world. Therefore, simply by hearing and chanting (śravaṇaṁ kīrtanaṁ), the sleeping soul is awakened from the slumber of material illusion to its original spiritual position.