I think an architectural comparison is useful, as the intonation of mantra is but walking into the first room. Various mental projections and shakti projections from your personal zone to others in the chanting circle with close coordination of harmony and intonation help create the basis of a common launch zone for getting through the crack into other levels of consciousness and alternate realities.
Closely listen and come into energy, sympathetic correspondence with one or several of your circle. Feel the cone of energy built. Push your shakti out with sound, breath, and Will. Listen with the most precision to hear the over tones both auditory and vibrationally, as in psychic tones.
Blast off! Feel the Others (non-physical beings) join the circle. They can be there! The ancestors are with us.
Guru Om! Om Bhairava!