# Can I use REW to measure echo in my room?



## liteglow (Jan 19, 2014)

I would like to improve my room acoustic, with removing echo, maybe improve sound and bass.

The sound is OK (well I have nothing to compare so OK in my ears), but when I clap my hands I hear clearly echo from the white flat roof.

I added 3 fiberglass rockwool panels in the roof, and I can clearly hear that when I clap the sound of echo is not there anymore.

But when playing music, there is not so much noticeable difference. And to remove the panels to check and put them back up fast to check is not that easy.

I also try to place a thick blanket on the walls, but I not so sure if I notice any difference in the sound, should I ?


So can I measure it in REW somehow ? I have the umic-1 


btw, I using the mirror tip when I place the acoustic damping plates.

I also wonder, can I measure if I need a bass-trap, and what difference should I hear?


cheers


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## tonyvdb (Sep 5, 2007)

Certainly, if you use the "waterfall" graph it will show you what frequencies are causing you issues. Make sure you set the graph grid to only display from 10Hz to 400hz as anything above is not really helpful.


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## Blacklightning (Nov 22, 2011)

Use the impulse screen. Measure just one speakers at a time.

Here is my right speaker in my room with nothing on the wall (Red line).
Now I placed a 1 foam pad on the back left side of my wall and measure (Purple line) 

You can plainly see that the pad makes the reflection at 9ms decrease.
Now place the pad somewhere else and you will see how it affects the original wave.


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## liteglow (Jan 19, 2014)

Thank you  I will certainly do a test when the kid is not sleeping.

btw, I use the sound loop from 20hz to 400hz ? 
I would have guessed that to measure echo there should be a ping or a spark like sound.


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## JohnM (Apr 11, 2006)

The impulse response is derived from the sweep, it is equivalent to using an actual impulse but without the need to use a signal your speakers could not faithfully reproduce. For reflection analysis you should use a full range sweep to 20 kHz.


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## liteglow (Jan 19, 2014)

My first waterfall test.
Not so sure what I am looking at here :dontknow:

This was a 10hz - 20khz sweep without using my subwoofers.


I can do test with one speaker, but what should I be looking at?
Is my room critical to echo or is it just fine like it is.


thank you



EDIT: I added the file with the sweep (again without using the sub) 

what can the the cause of the peak in drop about 220hz?


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## Talley (Dec 8, 2010)

I'm such a noob to REW but based on what I've seen..... thats alot of echo/ringing.


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## Blacklightning (Nov 22, 2011)

liteglow said:


> View attachment 77865
> 
> 
> I can do test with one speaker, but what should I be looking at?
> ...


I don't see the file. Please send your file so we can look at the data. 1 speaker only.


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## liteglow (Jan 19, 2014)

View attachment jan 14 18_16_30.mdat


Sorry, here is the .log file.
ONLY left speaker, no sub !


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## Blacklightning (Nov 22, 2011)

liteglow said:


> View attachment 77881
> 
> 
> Sorry, here is the .log file.
> ONLY left speaker, no sub !


Thanks
First I'm no expert, just figured some things out in the last few days.

Your room is very reflective where are your speakers and LP?
You have a big reflextion just after 5ms but your whole impluse seems high.

You have a problem at 62-64Hz that will need bass traps.

Send us a picture of your layout.


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## liteglow (Jan 19, 2014)

Remember that in the LOG file i added, there was NO sub and only 1 front speaker.


The measurements you see on this pictures is from my old readings where there is a loss where I sit :rolleyesno:

but there is nothing to do about that because of the size of the room.


and btw: the 2x12" sub is no longer in the picture.

Today I have 2x SVS pb13 ultra


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## Blacklightning (Nov 22, 2011)

liteglow said:


> The measurements you see on this pictures is from my old readings where there is a loss where I sit :rolleyesno:


Don't feel sad, it's not a loss where you are sitting, I would think that your position is okay. Did you try any of the previous tricks mentioned?


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