There are many papers besides Toole 1970 research paper. The head movement and reflection does play a part for externalization.
I am just wanting to experience that in a so called dry room. I believe my room with RT sub 0.2s qualifies for that.
Toole made the in head comment in the book no doubt but I just wanted to see more and be objective about it instead of relying on unknown recordings. Can I replicate them? How much dead should be the room? Do I get the same perception with different amplifier or speakers? I just want to be objective.
So besides stereo recording is there any situation where the external sound is heard inside the head?
Hi,
to be able to connect perceived sound to concepts, I think one should simplify and generalize all the details to be able to concentrate on listening and not thinking about it, think about the (written) details.
I'm sure you can figure out a listening experiment where you can study the phenomenon by yourself, listen what you actually perceive. Here is how to simplify:
Any dry sound (like white noise) listened with headphones gives you the inside head sound, what ever that sound is to you. I'm not sure if there is any other way to get sound localize inside the head than this: when sound has no spatial information your brain makes up something and what ever your brain does is easy to test, using dry mono sound with headphones.
Difference between this perception in headphones and same sound played back with a speaker system is mostly the local room reflections giving the sound some spatial cues so your brain doesn't have to make up anything, it can now localize the sound within the room, in front of you as thats usually where strongest and early reflections come from.
Simplified the effect is just Direct / Reflected sound ratio: if you took your headphones and started pulling them out from your ears, there would be some distance, from headphone to ear, where the room sound is loud enough to change the perception compared to when you had the headphones covering your ears and no spatial cues at all.
Sound level in room is function of room acoustics and directivity of the sources, and is relatively uniform in the room no matter where you or the sources locate. However, level of direct sound can be adjusted by speaker listening axis (toe-in) and distance from speaker to ear.
So, to get D/R ratio up so you could perceive your inside head (headphone) sound:
-increase direct sound: bring speakers closer to ears, listen on-axis. Easy and low cost, good way to experiment.
-decrease reflected sound: change room acoustics, especially early reflections that help localization and/or use narrow coverage speakers. Relatively difficult and costly.
In other words, you must somehow understand what is it that you hear, and no one else can help you with that, one must experiment. The above is something how I understand, and hear, this particular topic (what "inside head sound" sounds like to me, how to make it happen, and how it relates to my stereo playback system) and how I would experiment with it. There is no other way to understand it for me, because thats how I connect this particular topic to my perception. You must find your way to do it, understand your perception somehow, or be confused about it