origins of temples, chanting

I have no way to initiate this conversation topic other than to say that: 1)sound (aside from pain, suffering, disease, despair) has been my bridge to unity or love and absorption/surrender, 2) the effects of chanting and droning within a cave-like structure and sometimes hearing small segments of high-quality recordings of chanting from N. India (ie. Rajasthan) and such things as Muslim prayer calls (or, chants/calls in a similar vein) feel like a connection to some activities of people since time immemorial 3) I am questioning the origins/intentions of the earliest temples or temples of any specific peoples who may have tapped the power of such drones and chants within some "civilized caves."

I am not yet able to find any speculative writings on this topic area, but I would very much appreciate any input/suggestions of any person. Specifically, such things as speculation concerning the use of hollow mounds in England would be of interest. Any region/locale--worldwide--is of interest.

additional: if there be anyone in N. India reading this post, my heart... Shiva, is pulling me there and I shall be arriving next year to wander in search of home, love, and praise of God with others.

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Great topic.
It would seem to me that almost any of the human senses can be used as a "bridge to unity."

Touch, as in Tantra.

Smell, stimulated by incense.

Sight, as in mandala or internal visualization.

Taste, as in Eucharist.

And of course hearing. Hearing is one of the most interesting, as it takes so many aspects: koans, mantras, hymns, chanting, drumming, bell-tones--the list is long. My personal favorite is a more presumably modern technique of brain entrainment using binaural beats.

Here is quote from Holosync, one of several venders of this technology:

Each time you listen, this technology will give your nervous system a very specific audio stimulus through each ear, affecting a part of your brain called the olivary nucleus, and taking you into a state of super-deep meditation. In order to process and handle this stimulus, your brain will create new neural pathways between the left and right sides of the brain, until over time it has created a new structure that can easily handle the stimulus you're giving it.

The intention being to encourage a more "whole-brain" form of thinking.

In general, I would say that the ancients were pretty smart. They used the tools that they had at hand, whether that was stone to build with or the senses that God gave them. When people talk about lost knowledge of the ancients, the use of sound is one of the first things that I think of.
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