A few questions

[Swami Vishvarupananda]

> 1) Where can I find material relating to the teaching on creation being
> brought into existence by sound (ahaM) and on the mechanism by which
sound
> arises (parA, madhyamA, pashyantI, vaikharI)? The only reference I have
> found, to the latter part, was a bit in the chandogya upanishad.h.

This is an important part of the teachings of Kashmir Shaivism, which is an
advaidic system of the Tantras. I am giving you a few really thorough
references, though you will find some mention about this teaching in any
book on Kashmir Shaivism:

Paratrishika Vivarana, the Secret of Tantric Mysticism; English translation
with notes and running exposition by Jaideva Singh; Delhi,  Publisher:
Motilal Banarsidass

Sri Malinivijayottara Tantram; Sanskrit with elaborate and descriptive
English Introduction by Pandit Madhusudan Kaul; Butala & Company Delhi

Kashmir Shaivism, the Secret Supreme; Teachings in English by Swami
Lakshman jee; Universal Shaiva Trust, Srinagar Kashmir.