# How to identify where reflections are coming from?



## Guest (Jan 2, 2009)

Greetings All,

This may be off topic but it seemed as good a place to start as any ...

In a building that is very lively, is there anyway of identifying where the echoes are coming from?

Is there a device that can be pointed at a surface and used to estimate how much of the sound is coming from that direction?

It would take a while to explain what the questions are all about but a fairly thorough search of thre literature has not identified much. Hence the questions to the guys who get their hands dirty.

Regards

Roger Bowen


----------



## tcarcio (Jun 27, 2007)

I don't know of a device that will give you an exact readout as to what is being reflected. I just use the mirror trick to find out where they are. Maybe if you can find out how sound absorbant, if at all, the surface you are reflecting off of is you can figure it that way?


----------



## Mike P. (Apr 6, 2007)

Is the source of the sound an audio system? Do you mean the whole building or just a room? More information would be helpful.


----------



## Guest (Jan 2, 2009)

The source of the sound is a human speaker amplified by a PA system.

The sound system has been designed to be kept low, i.e. sound is not blasted around the building. The refelections should be second order effects and the question is where to place absorbent material to stop the racket building up. A simple answer is "everywhere" but I suspect that there is a better use of material to absorb the hot spots.

The building in question resonates in the key of C and RoomEQ plus FBQ has been used successfully to contol the resonance issues but reverberation continues to be a challenge. Hence the questions

Many Thanks

Roger Bowen


----------



## atledreier (Mar 2, 2007)

You can use the impulse plot in REW to get the distance to the different reflections. Then measure a string with this length, have someone hold one end at the tweeter. Wherever the other end touch a surface will be that reflection. Then do the next reflection in the same way until you have identified the major ones.

I see this sounded much more clever in my head, but the method works. Maybe someone can explain it better.

For general reverb the effect is by nature statistical, so no point absorbtion will lower reverb times.


----------



## JohnM (Apr 11, 2006)

You could also try the software described in this post: http://www.avsforum.com/avs-vb/showthread.php?t=822273 which will show you the first refelection points, the software itself can be found in post #199 of that thread (the original links no longer work).


----------

