Scientology was based on many of the old teachings and its creator admits to this in his own writing. He just sought to refine it. Make it more intelligible and accessible.
There are various methods of communicating with the spirit world and the presences that are there.
Meditation: One of the most easy methods, and the way most stumble across it, is meditations. At times in meditation one looses themselves enough in a deep open state that a spirit (often a guide) can communicate rather directly with them. There is no special method for meditative communication, you just use whatever technique you use. It can improve the likelihood by meditating when not fatigued or worried.
Ritual: For more focused efforts other methods can serve better. Any of you students of ritual? Directed rites or even just formalized prayer? Mantra use? The spiritual energies within you are not “within” you. Not confined to you. A solidly intuited prayer or mantra can often attune you to a specific sector of the spirit world and its agents, increasing the likelihood of contact. Even hermetic ritual induces a meditation like state, as does the wiccan. But most don’t juggle an openness with their ritual or prayer, and thus things either don’t work or don’t work as well.
More important than technique is intent, and any technique mostly serves to articulate your intent and focus your awareness. The spirits don’t “hear” sound. That’s a rather organic function and unless you are dealing with an elemental of some kind there is nothing to receive the sound.
Divination: Divination is another body of techniques that can permit spirit communication, and I don’t necessarily mean the hackneyed oija board stereotype. The planchete was an old French invention and much maligned as well as over hyped. Scrying is a classical method, and though orthodox Christianity reviles Nostradamus, his meditations and prayers were all to the Christian God. His personal method of scrying was ink poured into a bowl of water, and he was noted for having ink stained sleeves. The purpose of the focus in scrying is to produce a recursive loop in the optical lobes, thus temporarily suspending dependency on that in processing the world.
Necromancy: For some, more challenging is necromancy, although it’s not truly an independent method. This is dream interpretation, but more importantly dream induction as you practice the other methods.
In the Greek temple of Morpheus, it was just impassioned prayer and mild narcotics in the incense. The narcotics aren’t necessary, but other practices can induce a “narcotic” like effect, like yoga or tai chi. With deliberate and active focus before slumber, you can often induce a “prophetic” dream.
Now many of the purist schools revile the “dark” techniques though their own austerities are little different, if they are at all. Pushing oneself to a physical limit can often produce a broadly open state. The Native American shamans sought it to experience immersive contact with the spirit world, but less unpleasant methods can be used. For a short stint, I used techniques with a former partner to shift her into contact. She found the insights she gained from her guide quite useful, though the side effects were a little troublesome. Prolonged involuntary trance, and a potentially addictive euphoria. Though if other things were healthy, this isn’t really a bad thing. It can just permit bonding, if other factors permit. This is a reason why the tantras speak of their methods, especially from the Kama Sutra, as being a uniting between Gods and with the Gods. And though in my case I needed to serve as an operant, with patience and discipline both partners can commune.
Your thoughts are welcome. Be well friends.