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How to measure Rooms with High Ambient Noise

edechamps

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Main issues is high level of ambient noise.

As @RayDunzl explained above, as long as the signal you're measuring is 20 dB above the noise, you will achieve a measurement accuracy of about 0.05 dB (noncoherent 0 dB + -20 dB = 0.05 dB). Even just 10 dB (0.5 dB accuracy) would probably be good enough for room correction.

In addition, the windowing that is normally done on frequency response sweep measurements (including REW measurements, by default) will filter out most of the noise, so the effective noise on the measurement will not be as bad as the broadband noise you measured. This is even more effective on long sweeps.

Bottom line: don't worry about it. REW frequency response measurements are highly resilient to noise. Summoning @JohnPM to confirm.

I suspect some of the answers in this thread are confused because it's really not clear from your post whether you are worried about noise for the purposes of measurement, or for the purposes of listening. From the title of the thread I assumed the former.
 

dc655321

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It's greyed out in REW, when you select acoustic timing reference.

Do you know if there is a technical reason for that (I can't think of any, but that means nothing), or is it just an "oops" in the configuration space of the UI?
Perhaps @JohnPM could weigh in.
 

JohnPM

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Do you know if there is a technical reason for that (I can't think of any, but that means nothing), or is it just an "oops" in the configuration space of the UI?
Perhaps @JohnPM could weigh in.
Acoustic timing references are used when there isn't another way to get a timing signal to the input device, usually because it is a USB mic. Multiple sweeps with different input and output devices don't work well, especially with long sweeps, because of clock rate differences between the devices.
 

JohnPM

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Bottom line: don't worry about it. REW frequency response measurements are highly resilient to noise. Summoning @JohnPM to confirm
Bear in mind that the noise floor of a room as measured by an SPL meter is the summation of all the noise across the whole frequency band, the noise at any given frequency will be much lower. The sweep at any instant has all of its energy at a single frequency, so even if it is only 75 dB it will be far above the room's noise floor at that particular frequency, which will be diced into the buckets of an FFT of twice the sweep length.
 

RayDunzl

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I have high ambient noise from traffic. I've done something to try and reduce it and I've measured it. Knowing where on the frequency spectrum the noise is allowed me to try and deal with it.

To reduce ambient noise I installed a third line of glazing specifically for sound (with a large air gap) to go behind the existing double glazing.
index.php


Green - no glazing. Red - glazing.

Hmm...

I'm in a quiet neighborhood.

Red = peak
Black - live

Spectrum display

1565909579490.png


Just to compare...
 

Krunok

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Rather satisfied but Bass could be better. I have used Audyssey to clean it up but remain unsatisfied ,especially when I hear he bass from my headphones and other system. In some areas in the listening room bass is great .. at the listening position bass could be better.. both in HT and music modes.

Main issues is high level of ambient noise.

I don't think those 2 issues are related. For a start I suggest you post a measurement taken at your listening position (preferrebly averaged) so we can see what kind of a job Audyssey did and how it correlates with your dissatisfaction regarding bass.
 
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RayDunzl

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RayDunzl

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RayDunzl

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Still, you seem surprised that I have HF noise in the room. Could it be because my microphone is catching a sound from a notebook's cooling fan which is app 1m away?

I would first suspect differences in the microphone and ADC being used, and maybe calibration.

I match your settings and get this:

1565943779030.png


There are fans in the room.

Why is your graph so smooooth?
 

Krunok

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I would first suspect differences in the microphone and ADC being used, and maybe calibration.

I match your settings and get this:

View attachment 31478

There are fans in the room.

Why is your graph so smooooth?

Because I used 1/24 smoooothing. :D

My microphone is Daytonaudio iMMM-6, it's calibrated. It's plugged into microphone port of my Lenovo notebook so unknown ADC quality (probably not stellar, but my guess is it is sufficient for loudspeaker measurement).
 

RayDunzl

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Because I used 1/24 smoooothing.


Ok, 1/24 smoothing...

1565944702340.png


My microphone is Daytonaudio iMMM-6, it's calibrated. It's plugged into microphone port of my Lenovo notebook so unknown ADC quality (probably not stellar, but my guess is it is sufficient for loudspeaker measurement).

Probably.

Definitely better than nothing...
 

Krunok

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Well, here it is again, it looks like noise in my appartment is simply smooother. :D

Capture.JPG
 

Juhazi

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My living room, UMIK-1 with 90deg calibration

juhazi ambient noise.jpg
 

Juhazi

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Krunok et al. Did you check REW Preferences, which microphone feed is active? I double checked and tested by whistling that REW uses UMIK-1, but RTA screen title says it is Master volume.
 

Krunok

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Krunok et al. Did you check REW Preferences, which microphone feed is active? I double checked and tested by whistling that REW uses UMIK-1, but RTA screen title says it is Master volume.

Yep, all good - my microphone is connected via TRRS, not USB.
 

Krunok

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I don't think those 2 issues are related. For a start I suggest you post a measurement taken at your listening position (preferrebly averaged) so we can see what kind of a job Audyssey did and how it correlates with your dissatisfaction regarding bass.

But this thread is not about noise in our rooms so bump to the needed measurement from @FrantzM :p
 
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