Greg Taylor, Author of the Month for January 2008
Her Sweet Murmur (cont.)
By Greg Taylor
There's Nothing New…
The phenomena discussed so far — NDEs, entheogenic experiences, magical ritual — largely suggest that these sounds herald the onset of an altered state of consciousness. This appears to be confirmed when we survey mystical traditions from around the world, most especially those from the East, which are already well ahead of us in describing these sounds in connection with altered states. 
Beginning with the literature on kundalini, according to Sat Chakranirupana, written more than five hundred years ago by the Bengali yogi Purnanada:
The sleeping kundalini is extremely fine, like the fiber of a lotus stalk. She is the world-bewilderer, gently covering the "door" to the central Great Axis. Like the spiral of a conch shell, her shiny snake-like form is coiled around three and a half times; her luster is like a strong flash of lightning; her sweet murmur is like an indistinct hum of swarms of love-mad bees.)
From the classic treatise on Hatha Yoga, Shiva Samhita, we learn of the 'sounds' that a practitioner is likely to experience:
The first sound is like the hum of the honey-intoxicated bee, next that of a flute, then of a harp; after this, by the gradual practice of Yoga, the destroyer of the darkness of the world, he hears the sounds of the ringing bells, then sounds like roars of thunder.
Another of the classic yoga texts, Hatha Yoga Pradapika, also describes sounds:
In the beginning, the sounds resemble those of the ocean, the clouds, the kettledrum and Zarzara (a sort of drum cymbal); in the middle they resemble those arising fromthe Maradala, the conch, the bell and the horn. In the end they resemble those of the tinkling bells, the flutes, the vina, and the bees.
Moving from Hinduism to Sufism, we find this extremely accurate description of sounds heard during the induced altered states of that particular mystical tradition, as described by the Sufi master Hazrat Inayat Khan:
An adept who practices Shaghal, after some time will have an experience of that Shaghal during times when he is not practicing. He will hear sounds of the sphere in ten forms: in the form of the buzzing of the bees, in the form of the bells ringing in the ears, in the form of whistles blowing, in the form of the fluttering of the leaves, in the form of the running of the water, in the form of the sound of Vina, in the form of the cooing of the wind, in the form of the crashing of the thunder, in the form of the music of the spheres, in the form of the song of the angels.
It pays to revisit this final passage after reading the complete essay — Hazrat Inayat Khan obviously knew his topic!