# Impulse responses



## angeloconto (Feb 22, 2013)

Hello everybody. I did some impulse response measurements in my music room. It's a room mainly dedicated to teaching activities, and I'd like to make it sound as good as I can. I made a QRD Schroeder diffuser, placed in the middle of the roof, and now I'd like to understand what I can do to improve the acoustics. I attach the drawings of the room with the source and receivers, and measurements from source in A and receiver 1.
Hints from the experts are very welcome !
Moreover I don't quite understand the reason why the spl response at, let's say, 1000 Hz, is higher than it is at 2000 Hz, but the rt at 1000 Hz is lower than rt at 2000 Hz. I think: higher spl>lower damping>longer decays but something is missing...
Schroeder frequency should be 140 Hz.


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## lesmor (Dec 30, 2009)

Unfortunately the scale of your graphs are not as recommended on the REW site for posting 
I think you need to supply more detail on the sources that seem to be scattered around the room
Also are the room dimensions in metric?
Please supply the room lenght,width and Height
It is also better to attach the metadata files for someone to look at


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## angeloconto (Feb 22, 2013)

Hi Lesmor,
yes the measures are in metric, and we have to subtract some 30 cm because of the insulation. So they are: lenght 10,63 m, width 5,39 m, heigh 2,8 m.
I recorded the impulse response placing the source (Genelec 8040) in the various positions I drawn on the plan.
About the graphs: I upload this new graphs, hoping it will be better. What metadata are ?


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## angeloconto (Feb 22, 2013)

graphs


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## lesmor (Dec 30, 2009)

angeloconto said:


> Hi Lesmor,
> yes the measures are in metric, and we have to subtract some 30 cm because of the insulation. So they are: lenght 10,63 m, width 5,39 m, heigh 2,8 m.
> I recorded the impulse response placing the source (Genelec 8040) in the various positions I drawn on the plan.
> About the graphs: I upload this new graphs, hoping it will be better. What metadata are ?


Hi angeloconto
The metadata is your REW files which you can add as an attachment
This will allow people to view and manipulate the data on their own copy of REW
To be clear I am no expert just trying hopefully to point you in the right direction
I am sure someone with more experience will eventually come and in and advise you.


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## angeloconto (Feb 22, 2013)

Ok, I have attached the rew files. Looking forward for some hint !


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## lesmor (Dec 30, 2009)

angeloconto said:


> Ok, I have attached the rew files. Looking forward for some hint !


Thanks
Have you ever considered contacting GIK Acoustics?
They will look at your space and data and offer free advice.


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## lesmor (Dec 30, 2009)

@angeloconto
Had a quick look at the data
I am in no way a expert 

What SPL did you set for the measurement as it looks to be too low?
What microphone are you using?
The Graph seems to roll off at 70 Hz is that the -3db cut off of the source if so there is no usable bass data.
Looking at the impulse response there seems to be a lot of reflections. 
Sorry for all the questions but just trying to get a feel of what you are actually looking for.


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## angeloconto (Feb 22, 2013)

Hi Lesmor,
I didn't set a reference level for spl, just check that the level was ok for rew
mic: Dayton 8098 with calibration file
the lower cutoff frequency of Genelec 4080 from technical spec is 45 Hz


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## lesmor (Dec 30, 2009)

angeloconto said:


> Hi Lesmor,
> I didn't set a reference level for spl, just check that the level was ok for rew
> mic: Dayton 8098 with calibration file
> the lower cutoff frequency of Genelec 4080 from technical spec is 45 Hz


From what I can gather your readings are too low.
What is the noise floor of your room?
In the meantime perhaps have a look at this video


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## angeloconto (Feb 22, 2013)

the rooms is very quiet. I don't have more precise data as I don't have a calibrated spl meter.


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## robbo266317 (Sep 22, 2008)

angeloconto said:


> the rooms is very quiet. I don't have more precise data as I don't have a calibrated spl meter.


Do you own, or can you borrow, a smartphone?

There are free Decibel meter/SPL Apps available that are good enough to set your levels for testing.


.


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## angeloconto (Feb 22, 2013)

is it importante the calibrated spl level to understand the response of the room ? I mean, room modes and reverberation time.


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## angeloconto (Feb 22, 2013)

no other comments ? Is this off topic ?


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## robbo266317 (Sep 22, 2008)

Sorry, I missed your post.

It isn't essential but it does help by making all graphs the same scale so that people can compare them to theirs and offer advice/opinions.


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