Understanding Acoustical Pressure Zones

Hi TuneLand

Perhaps the most important topic to the industry and hobby of listening to music. This is the topic of pressure zones, what they are and how they make sound and how they fit into everyones listening.

To do this I made a search of some different areas on tuneland that talk about zones, so this is the gathering place as we paint the picture so it is understandable and practical.

the following are some archived threads on pressure zones



http://www.michaelgreenaudio.com/forum/viewtopic.php?t=642

http://www.michaelgreenaudio.com/forum/viewtopic.php?t=290

the pressure zone controller

http://www.michaelgreenaudio.com/forum/viewtopic.php?t=320

more from Jim Bookhard

http://www.michaelgreenaudio.com/forum/viewtopic.php?t=254

Some where along the line we went from simple physics to bad engineering.



How did the audiophile world get mixed up and start thinking that soundwaves are straight lines? What's worse is building a false science around something that should be pretty common sense.

Here is what a stereo sound source looks like in a room.



If my room is done properly, using the attributes of the pressure zones I should be able to stand almost anywhere in the room and get close to the same volume level, plus or minus the natural rise and fall of each pressure zone and along the laminar parimeters.

There is nothing in science that tells us that the following happens.



If a sound wave was 2 dimensional it would respond at the wall more like this.



What we have found in our testing is that there is an acoustical plane that developes on any surface where the on coming wave meets with the reflective wave. We call this the laminar line or laminar flow.

The next part we need to know about that affects the pressure zone is room loading.

Room loading happens when the sound waves meet at intersections such as the corners and midseams and the mid wall ceiling or floor.



Here's a 2D look at the loading and laminar flow together. Keep in mind the floor and ceiling are doing the same thing as the walls.



All rooms because they are enclosed build sound pressure. Here's a look if the speakers and chair were gone.



Your probably starting to get the picture of how powerful the room is and how big of a role it must play in the stereo's sound. It is without a doubt the biggest component.

A misconception is that the speakers play independent of the room, but lets think about this. How can a speaker play without the room? Air pressure is a function of the room not the speaker. The speaker is a vibrating source that sends the music signal into the air in the room but it's the room that amplifies this signal. A loudspeaker can not play louder or over power what the room is doing. You may think your listening directly to a loudspeaker but if this were the case the music would sound like it was coming directly from the speaker and there would be no stereo image to speak of. The sound would be very sterile as if someone cut away the music.

Take a look at the misguided view of the speaker minus the room if it were possible. Notice how much of the sound waves are cut out.



The only way to remove the room would be to hook a tube from the speaker to your ear cutting out the room altogether. Nope, far better to use the room, and why not? The room can be a wonderful tool that allows you to recover much of the content rather than trying to cut the acoustic information out.

This is why I named the product RoomTune and started the phrase "Roomtuning". We don't want to get rid of the biggest component but use it as the most important and final part of the audio chain. Once you accept this as the "music producer" you can view the hobby with more accuracy.

Let me show you my favorite way to listen and why.



Whether I chose to listen long or wide I find that using the room gives me, one a far bigger image (more real life size), and two a lot better tonal balance.

See the curved loading parts of the room? These are my pressure zones. Some of them depending on the types of walls you have and dimentions of the room plus what is in the room will vary the size and location but this is a fairly true placement guide.

I made the drawing simple but if you saw these they would actually look like spheres. Acoustical spheres hosting the sound of what ever the source is putting into the room.

Why are the speakers and my ears sitting right in the pressure zone? Because that's where the sound is at it's most developed stage in the rooms voicing. Those who chose to be in a weaker part of a pressure zone can but I find this is where most of the musics meat is. I also like to be inside the musics envelope so I put the speakers on my side of middle, catching a fair amount of the zones pressure if I can. If I however want to be in the extreme soundstage envelope I'll move the speakers closer or further away from the walls to pick up a nice boost.

You might try this and say this doesn't sound right. That's because we haven't started voicing the pressure zones themselves yet. There are three parts to voicing to keep it simple.

ears, speakers, pressure zones



here are the most obvious places to start treating your pressure zones

the pressure origins



Here you can change the sound of your room dramatically and it's not only about turning the volume of these pressure zone origins up or down but voicing them.

here's a look at an RT and RTD2 setup controlling the main on wall areas and main soundstage pressure zone



a view from your listening chair