What method (equipment / app / process) do you use to identify room modes?

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2FlyingYorkies

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Just curious how everyone goes about identifying "room issues" with frequency response? There are plenty of options out there: free/cheap Real Time Analyzer phone apps; more expensive dedicated analysis gear; "Do it by ear" methods; reliance on digital room correction; waiting for a buddy to point out something that you hadn't even noticed, and so on...

How you go about fixing what you find is probably a different thread, and one that's been covered pretty well in the past. This thread is intended to cover how you go about identifying the unique peaks and suck-outs in your room.

This came to mind for a couple of reasons: 1) I'm trying to work through it myself without much prior experience, and I'm just not convinced that I've found everything that needs fixing; 2) a local retailer who has a good history of setting up high end systems demoed a fairly recently set up pair of Magico S5's for me, and a couple of days after my audition (which left me underwhelmed, by the way) called to say I should probably come back and try again, because he'd found and fixed a major bass suck-out almost exactly where the prime listening seat was in his room. If the more contentious retail pros have trouble, what's an enthusiastic amateur supposed to do?
 
2FlyingYorkies said:
Just curious how everyone goes about identifying "room issues" with frequency response?
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IMO, it helps some form of "reference", as to what things are supposed to sound like. Mine is unamplified acoustic instruments, orchestras, big bands, small ensemble, etc all the way down to solo piano, etc.
That makes it a bit easier when trying to judge frequency domain issues in listening rooms imposing their own "sound" atop the recording. Then there is actual listener training for listening to reproduction devices, like loudspeakers.
programs like the Harman , Klippel and Philips Golden ears, which will train one to identify frequency domain problems, resonances, etc., just like one would train to run a marathon, not by talking about it online, but actually running, then having that training tested in an actual race. Imaginary skills won't work too well there come race day.:)
Once one determines what sound one is after and how to identify problems preventing such goals, then learning how to measure...and far far more important, how to correlate what is measured to sound, the a combination of listening/measuring several time, will either achieve, or move one much closer to goal.
When you and your Dr look at an MRI, you both see the same thing, but the interpretation and comprehension of what is seen is vastly different, due to the Dr's training.
It's critical to understand what one is measuring, the limitations of any single "snapshot" measurement, how to combine multiple measurements and finally, correct interpretation.
Being multi-dimensional - listen/measure, is better than totally one dimensional by capacity.
As you note, lots of measuring options now, even with smartphone (I use AudioTool w Dayton mic w/ my LG) as well as free software like REW (another favorite of mine).

cheers,

AJ
 
2FlyingYorkies said:
Just curious how everyone goes about identifying "room issues" with frequency response?
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I have used Dr. Jörg Hunecke's online tool with very good results.
The calculator will give you a very good approximate of your room freq response.

Link: https://www.hunecke.de/en/calculators/loudspeakers.html

Plug your room's numbers (approx) into the Room Acoustic Calculator tool.
Choose the different conditions that describe your room construction etc.
Add the speaker configuration you have. (again an approximate will do)

The tool gives you a map of the room response at the bottom left.
You can drag the speakers around on the map to see how their position changes the freq response.

For lower frequencies, use the Eigen modes tool to see your trouble spots.
https://www.hunecke.de/en/calculators/room-eigenmodes.html

I hope that you find it as useful as I have.

Regards.
 
That's an interesting website, Nikhil. My room is irregularly shaped, but if I approximate it as a rectangle and add a subwoofer, the bass response nulls are very similar to what I think I'm hearing in the room (I don't currently have a sub, but my main speakers are probably more full range than the programmed sample).

I've always known that my large, open, irregularly shaped room (kitchen, dining, living/media, and entry/stairwell all in one) is an acoustic challenge that won't be easily modeled mathematically, or easily fine tuned. But it's nice to see even an approximation that seems to point in the right direction.
 
Glad you found it useful. It gives you a good idea of what could be going on.
The best thing is the ability to evaluate alternate speaker positions or even room layouts.

In my case I moved my living room setup along the long wall after using this tool.
 
Nikhil said:
I have used Dr. Jörg Hunecke's online tool with very good results.
The calculator will give you a very good approximate of your room freq response.

Link: https://www.hunecke.de/en/calculators/loudspeakers.html
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Nikhil, have you measured to confirm the accuracy of this simulator? I'm extremely skeptical it can simulate a real room/speaker response and intend to do a sim and then actual measurement. Unfortunately I don't have the typical monopole box speaker to do so at the moment but can fashion one for this purpose. Should be interesting.

cheers,

AJ
 
I use a spreadsheet called MRSS to get a rough idea of what is going on, then follow up with an actual measurement using Doug Rife's MLSSA card in an older PC.

The spreadsheet and online calculators are ok, they tell you where the modes will be, but they don't tell you how strong the modes are going to be. For that you have to measure, and even then the measurement is dependent on where your source is and where you position the measurement microphone.

I just did a friend's new listening room and the spreadsheet calculated multiple resonances near 50 Hz and some others around 100 Hz. Measuring the room, the 100 Hz resonances were very prominent, the 50 Hz ones not so much, which was totally contrary to my intuition.

There are a bunch of sound card based measurement systems out there - with some research and practice they may be usable.

Tom
 
If you're reall serious about it, room analysis is work! I've spent a couple of hundred hours playing with this. I use REW and measure with actual room treatment and system placements. Any phone consultations or on-line tools that purport to tell you what your room issues are almost useless.

There is a significant learning curve with the REW software, but it's cheap and very effective. Note that there are individual measurement results, flatter in-room frequency curves for example, that might appear better on paper, but that actually sound worse (issues of direct versus reflected sound for instance)! Just because you get different measurement results, doesn't mean you can hear the difference. How do you determine what the best reverberation time, waterfall plot or group delay plot is possible for your room and where you should make trade offs with one of the other parameters? It's still trial and error, very much requires listening, and is a bit of an art. Even if you find a problem, there are low frequency room modes below about 60 Hz that aren't easily rememdied because the bass traps would have to be enormous.

Having said all that, it's still worth it. Of course, you could always call in an expert and pay for it, but there are more than a few instances of people paying for room analysis that decided to start all over again. If I were to do that, I'd call JS and it'd be money well spent.

Oh, there are some simple things you can do. Buy a laser distance meter and make sure your speakers are equi-distant from the listening position, have similar tilt and height, and are positioned symmetrically to the walls. Try to neutralize impacts of asymmetry in room boundaries with placements or reflectors or absorbers.


Good luck!
 
AJ Soundfield said:
Nikhil, have you measured to confirm the accuracy of this simulator?
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AJ, I've always used the free online tool only to get a general idea of a room.
Approximating the listening space itself gives you at best a guestimate.
However, I can confirm that it is still a very good one.

The engine behind the software is pretty solid. I have no reason to doubt that if you provided them with an accurate room layout they would be able to model the room acoustics without a problem. The engine is used by several architectural consultants in Germany.

You could write to Dr. Jörg Hunecke for more info.
Link: https://www.hunecke.de/en/index.html
 
Nikhil said:
The engine behind the software is pretty solid. I have no reason to doubt that if you provided them with an accurate room layout they would be able to model the room acoustics without a problem. The engine is used by several architectural consultants in Germany.
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Nikhil, the problem isn't the layout, it's the lossiness (how much is reflected, absorbed, attenuated or just pass through) of each boundary, walls, floor and ceiling. there is no way for you to know that other than a general description. So there is also no way for the software to generate anything with accuracy. real rooms have far more complex lossiness than a best guess for a wall, especially when those wall have openings, windows, etc.
That is precisely why one must measure to confirm any simulation. I use a lot of sims when designing, before anything is built, but measurements are the final say there.
As mentioned, once I get some time and monopoles lashed up, with use that sim and then post real in room measurements for comparison.

cheers,

AJ
 
W9TR said:
... even then the measurement is dependent on where your source is and where you position the measurement microphone...
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I've used the XTZ Room Analyzer II Pro kit. However, measurement results can vary quite a bit with just minor changes in mic placement, even if averaging multiple measurements. It's a useful starting point, but not a perfect substitute for attentive listening after experimenting with speaker/sub placement. I plan to try REW as well, down the road.

Also (still) patiently waiting for Jim Smith's TTSB!! :skeptical:
 
TTSB Book One is done. TTSB Book Two 2/3 done. CDs 2 & 3 - 22 tracks - from my RoomPlay system/room voicing playlist - are FINALLY fully licensed, awaiting final mastering completion. CD 1 - mechanical tracks - also at mastering. DVD to be produced when books & CDs are done.

Electronic room DSP is potentially OK, but ONLY after optimum location of listening seat - the Anchor Point for all else, and best possible speaker set-up (based on working from optimal seating location) are accomplished organically (making the DSP have to work less hard). There’s a LOT more I could say re DSP, but it’s too complicated to discuss here.


Sent from my iPhone using Tapatalk
 
Jim, you saying you have another DVD coming. I had the first one. Lost it somehow. It was helpfull. Not sure I get much from quarter notes if I see them. Didn't you have a kickstarter for your second DVD?
 
Kingrex said:
Jim, you saying you have another DVD coming. I had the first one. Lost it somehow. It was helpfull. Not sure I get much from quarter notes if I see them. Didn't you have a kickstarter for your second DVD?
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Yep. Back when it was a book, CD, & DVD. Seriously late in delivering, but finally making real progress.
 
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