When the Kundalini rises it makes sounds. And the sounds that are heard in the different chakras can be pronounced in the following way – these pronunciations are being used in the phonetic language of Devanagari, which means ‘the language spoken by the Devas’.
At the Mooladhara, where there are four petals, the sounds are: [vum, shum, sshum, sum]. Out of which the last, sshum and sum sounds are very close, but the difference is - when the snake hisses it makes this sshum – the third sound. So, vum, shum, sshum, sum.
At the Swadishthana, where there are six petals - it makes sounds, six sounds. [Bum, bhum, mum, yum, rum, lum.]
Manipur it has ten petals. It makes the sounds dum, dhum, num, tum, thum, dum, dhum, nnum, pum, phum.
At Anahata there are twelve petals. It makes the sounds km, kum, gum, ghum, chum, chum, jum, jhum, tum, thum.
At the Vishuddhi, where there are sixteen petals, it makes the sounds of all the vowels – a, aa, i, ii, u, uu, r, rr, lr, lrr, e, ai, o, ou, um, ahm.
At the Agnya chakra it makes ha, ksha.
At the Sahastrara one becomes thoughtless and no sound is made, but the pure Anahata, meaning the throbbing in the purest form as in the heart is all.
When all these sounds are sounded together and pass through the spiral of the body, if the body is like a conch, the sound that comes out of the synthesis is AUM. Like the seven colors of the sun ultimately become white rays, or you can say the golden colored rays.
H.H.Shri Mataji Nirmala Devi, extract from Talk given in Hampstead, London, October 1978 (1978-1014)
Bija Mantras 1978 by Sahaja Library