Justin,

Sounds like you have a few retrievals that are just waiting to occur. You are right, these may reflect entities which are either part of your spiritual cluster or part of the building you live in.
From a technique perspective, you are 90% towards getting conscious retrievals. As you were falling asleep, you heard these voices. This state of mind is probably perfect for retrievals, although you may or may not be able to get vivid visuals at this stage.
First step is to learn more about the retrieval techniques that Bruce teaches. Not only will you get helpful hints, but you may also be able to ease your mind as to what's going to transpire.
Secondly, you are going to have to open up the "gate" again and get those voices. Then, you can insist that only one voice comes through. From there, you can try to communicate with this one voice and try to retrieve it by saying something like "do you see a light? move towards the light" or discuss where it thinks it is. (I'm sure other people have some better ideas)
Anyways, don't worry about failing to retrieve. I mess up all of the time. Not to mention, I had a pretty bad losing streak in the beginning.
Your "voices" are really a gift, in my opinion, because it gives you an opportunity to become aware of that special state of mind that allows you to conscious explore the spiritual realm. Fear is the most common stumbling block. But you can overcome it with time as you realize nothing bad is happening to you.
-mike

This is such an interesting and important question, I hope you will reply back some time when you have had a chance to test out the suggestions given to you and report on what you were able to get to work for you.

I don't think that every time you sense the presence of other beings that you are on the verge of a retrieval. After all every time you walk out your front door, you don't just go to the grocery store. Surely there are many places to go when we walk out the door of waking conciousness. We just haven't figured out the road signs yet to determine where we are.

Years ago (probably before Bruce even went to TMI)that would occasionally happen to me...I would be falling asleep and think I heard a conversation going on and wake myself up only to find myself alone. It was a curiosity because there was no one else to discuss it with and I had no idea how to figure this out. I don't know what kind of bleed-through was occurring. (now I have an overly busy life and I fall asleep too fast).

I wish there was more discussion of this because I think this is a crucial point. Surely others have some examples?