Development and Deciphering Strange experience of Location of Sound in Room

[umutmt]

Hello there,

I was listening Tommy from Who and there was a stone rubbing sound in music plays in a rhytm.

I experienced my little computer monitors plays cheap sound in front of me but that rubbing sound was coming from just my right side. There was a niche in the wall and I think sound was coming from there.

I thought if I can make niches , boxes in my walls and listening each of my acoustic guitars notes from strange locations , it would be excellent.

Can you explain and tell me how can it be done ?

Thanks,

Mustafa Umut Sarac
Istanbul

 

[Pano]

Well that's an odd and unusual request! It does sound like a fun experiment (tho maybe it belongs in another part of the forum).

Have you done any further tests? For example, does that niche in your wall pick up any other sounds? If you move your laptop or yourself, does the effect go away? What if you put a cloth in the niche?

I've heard some strange sound location effects, but mostly they had to do with speaker phase. If you can create a similar effect with holes in the walls, that would be something fun and interesting.

 

[umutmt]

My room is extremelly crowded and I did not try anything before. I said niche but the real thing its a empty place in between furniture , wall and window.

I think speaker phase is interesting subject. Can we control phase of the guitar or speaker with diffractive element to get sound location effects ? I think I read something like it.

And can we create speaker phase in the desired locations of the room with changing the room ?

Is there any article for them ?

 

[rayma]

My room is extremelly crowded and I did not try anything before. I said niche
but the real thing its a empty place in between furniture , wall and window.

First rule out a room effect. Drape a large cloth or rug over the area where the sound
seems to be coming from. If you still hear it, then it's probably not room acoustics.

Then try reversing the channels, and see if the same effect happens on the other side.

 

[scottjoplin]

I think speaker phase is interesting subject. Can we control phase of the guitar or speaker with diffractive element to get sound location effects ? I think I read something like it.
And can we create speaker phase in the desired locations of the room with changing the room ?

I'm not quite following, do you want to use reflections to shift the image location? Phase (time delay) is used to change image position in the stereo mix

 

[umutmt]

I am not expert. Reflections can meet at some locations to construct new sound sources.
I think similar is done with ultrasound experiments. You can hear the music in desired location but no one can not hear it except dancing couple.

I changed the speaker locations and angles and now I cant make experiment.

May be time delay can be used in room with the help of surfaces or boxes.

I am not expert again.

I want two things , stereo plays but soprano and bass plays from top of the room , orchestra bottom , mezzo far right , violins left ... etc. But there will be only small stereo speakers.

second thing , classical guitar plays , first fret comes from top , second fret comes from the bottom etc

what can be done ?

 

[scottjoplin]

Reflections meet and interfere, constructively or destructively depending on the frequency and phase so you get what's called comb filtering. A single reflection, say, from a side wall will cause the image to be wider

 

[scottjoplin]

I want two things , stereo plays but soprano and bass plays from top of the room , orchestra bottom , mezzo far right , violins left ... etc. But there will be only small stereo speakers.
second thing , classical guitar plays , first fret comes from top , second fret comes from the bottom etc
what can be done ?

That's done in the mix, you have no control (unless you get hold of the master tapes and DIY!)

 

[umutmt]

I have no control on record but I have control on room and speakers and I experienced its possible. Which forum or email list do you advise ? stereophile ? let me try.

 

[scottjoplin]

But you can't move individual instruments around

 

[Pano]

You sort of can with phase tricks. Different ranges can seem to come from different places depending on how the phase is warped. Virtual surround relies on tricks like that.

 

[umutmt]

How can I warp the phase in the room ? Who can do it , what kind of engineering class teaches that ?

And warping phase can or cant be done with diffractive element ?

I thought to place two circular , one in front of other , diffractive element in the place of sound hole of a classical guitar , tunable ?

Lets do calculations less but the experiment more for a minute.

What would it be needed to make a classical guitar sound hole diffractor , what would be it like ?

What is the diameter of square or round holes in the diffractor.

I will be needed to cut some wave and allow some part of wave .

What is the approximated dimensions of holes and their distances and pattern of that filter ?

And how can I wrap the phase in the room ? Do I need ray tracing software ?

Is there a paper for such calculations for diffractive acoustic filters and room design ?

 

[scottjoplin]

Pano said different ranges, not different instruments