Listening Room Intelligibility Test

Rutgar · Jun 5, 2011

Hi Art, Great topic. Just to clarify what I'm understanding (I do happen to have the Stereophile Test CD 2):

This test indicates acoustics issues, and not gear issues?

When I did the headphone/loudspeaker comparison, the difference I noticed on the loudspeaker playback, is as the frequency goes up and then back down, the 'clicks' seem to slowly fade in and out, becoming more and less prominent.

So, the reason why the 'clicks' are warbling is due to room interactions, especially as the volume get louder (bring more of the mechanical structure of the room into play.)?

I have always noticed that the louder I play my system, especially with more complex or 'busy' music, that sometmes things start sounding like a huge ball of a confusing mess, and not very musical. In the back of my mind, I always blamed this on my amplifiers switching from pure Class A, into A/B mode (since at louder volumes, this is a very likely occurance). But what I am reading here, it sounds more like it is an acoustics problem. BTW, I'm not the only one I know who has experienced this 'ball of mess' sound when cranking the volume up.

I would love to record what I am getting. But I have no means to do so, at this time.

fas42 · Jun 6, 2011

Rutgar said:
I have always noticed that the louder I play my system, especially with more complex or 'busy' music, that sometmes things start sounding like a huge ball of a confusing mess, and not very musical. In the back of my mind, I always blamed this on my amplifiers switching from pure Class A, into A/B mode (since at louder volumes, this is a very likely occurance). But what I am reading here, it sounds more like it is an acoustics problem. BTW, I'm not the only one I know who has experienced this 'ball of mess' sound when cranking the volume up.

Looks like no-one else is going to react, so I will just be my usual tiresome self and point out what I perceive the problem to be. Your situation is exactly what I have experienced on myriads of systems, including the setup of the friend that I've been helping out.

As you thought before, I would lay the blame virtually entirely on the amp: a combination of the class AB operation and a power supply not able to do its job properly guarantees that the sound quality plummets at higher sound levels; something that people typically blame the speakers or room for. If you inserted a power amp that was dramatically over powered for the job, or swapped to very efficient speakers like horns, or just properly engineered the whole setup so that it didn't fall apart as you up the volume control then the result would be dramatically better sound at high listening levels ...

Frank

Rutgar · Jun 7, 2011

Hi Frank,

My amplifiers are Parasound Halo JC-1's. And at the volumes I'm experiecing this, I know there is no way the amps are running out. Which is why I sort of blamed this issue on the A - A/B threshold. Plus, I have experienced this with many different speakers on these same amps (and same room of course). One friend in particular who also has this occur, is using a pair of large Luxman stereo amps, bridged in mono, but are also Class A - A/B. And it looks like erroneously, we might have blamed this phenomena on the A-A/B thing.

To get started, I would like to record my sound to be evaluated for the MATT test. But like I said, I don't have the equipment. I'm assuming all that is needed is a computer (I have that), a mic and the necessary software to record a wave file from a live source? If so, anyone here have recommendations here on a mic and software?

Bruce B · Jun 7, 2011

Rutgar said:
Hi Frank,To get started, I would like to record my sound to be evaluated for the MATT test. But like I said, I don't have the equipment. I'm assuming all that is needed is a computer (I have that), a mic and the necessary software to record a wave file from a live source? If so, anyone here have recommendations here on a mic and software?

For software you can use either Reaper or Audacity. Both are up to the task.

Next, you will need a mic and mic pre-amp. There are several that Ethan recommended for room measurements. You can look HERE for suggestions.

Rutgar · Jun 7, 2011

Okay, thanks for the link Bruce. I will scope it out and see what I can get going.

Edit: I ordered the Behringer ECM8000 mic (calibrated) and one of the external sound cards recommended. (funny, the 'E-MU Tracker Pre USB 2.0' was out of stock everywhere, so I ordered the 'M Audio MobilePre USB').

BTW Bruce, it may interest you to know that my woofers to convert my MMTwo's into MMThrees have been ordered.

Bruce B · Jun 7, 2011

Rutgar said:
BTW Bruce, it may interest you to know that my woofers to convert my MMTwo's into MMThrees have been ordered.

Cool!

My friend Andrew had the MM2's and when he put the upper woofers on he said it was a dramatic change.

Steve Williams · Jun 7, 2011

Bill

congrats on that. You will be a mighty happy camper

Art Noxon · Jun 23, 2011

Rutgar said:
Hi Art, Great topic. Just to clarify what I'm understanding (I do happen to have the Stereophile Test CD 2):

This test indicates acoustics issues, and not gear issues?

When I did the headphone/loudspeaker comparison, the difference I noticed on the loudspeaker playback, is as the frequency goes up and then back down, the 'clicks' seem to slowly fade in and out, becoming more and less prominent.

So, the reason why the 'clicks' are warbling is due to room interactions, especially as the volume get louder (bring more of the mechanical structure of the room into play.)?

I have always noticed that the louder I play my system, especially with more complex or 'busy' music, that sometmes things start sounding like a huge ball of a confusing mess, and not very musical. In the back of my mind, I always blamed this on my amplifiers switching from pure Class A, into A/B mode (since at louder volumes, this is a very likely occurance). But what I am reading here, it sounds more like it is an acoustics problem. BTW, I'm not the only one I know who has experienced this 'ball of mess' sound when cranking the volume up.

I would love to record what I am getting. But I have no means to do so, at this time.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Hello again, I’ve been out of the loop for a while and finally things are back to normal.

We’ve been exploring a certain kind of test. It is a modulation transfer function. It measures the ability of your sytem to send morse code. Da….dadada…..dada and so on. This is a dynamic text because it shocks your system and the after shock is what we are interested in. You could listen to Morse code over headphones and have no problem reading the signal. Put put the speaker at the far end of an empty racquetball court and try to read the signal, you can’t. the reverberation is so great that the distinctness of each sound I lost and the whole sound is just noise.

It’s not your electronics that is wrecking your ability to hear the signal, it’s the room the electronics are in that is wrecking the distinct quality of each tone burst, each …da.. There are two parts to room acoustics. One is always there, the acoustic one, reverberation. The second one only kicks in when the sound level is loud, so loud that it can shake the walls, windows, doors, lamp shades, equipment panels, heat fins, floor, ceiling, picture frames, cabinet doors amd backs, drawer bottoms and so on.

Any surface that moves makes sound, especially if it moves back and forth, vibrates. A speaker cone moves back and forth and it make sound. Once these other surfaces in the room begin moving, they make their own sounds, adding to the speaker which is making its sound. When we play the room quiet to medium loud the speakers don’t put out enough energy (sound presure) to shake anything. The natural friction of materials absorbs as much energy as is deforming it and the material stays calm. However, play the room loud and we now are putting more energy into the objects than they can naturally get rid of and so they become charged with vibrational energy. When the music changes, energy is no longer being fed into that panel and so that panel discharges, filling the room with its own sound.

Iin general, audiophiles know how loud they can play their room before it begins to breakup. Just like a loudspeaker if you over drive the diaphragm, push it too hard it will change shape and go into some vibration mode, it’s called cone breakup. Cones soften over time due to the amount of shaking they suffer. In recording studios that are very busy, playing music all day and all night day in and day out, they have to recone their woofers every couple months. The cones soften and begin to buckle under load and they start to sound weird. I don’t know of a test for cone breakup just now. I’ll check around. Does anyone out there know about cone breakup?

I’ve never heard of a sound system playing a room so hard for so long that it begins to soften the room would mean it goes into mechanical resonance at lower sound levels. But, you never know…

Hope this helps you understand this loudness sound barrier effect a little better.

Art Noxon

PS I think we are focusing on the clicking effect too much and we need to be listening to the garbling aspects of the MATT test. I'm sorry to have brought too much attention to this tiny detail.

Steve Williams · Jun 23, 2011

welcome back Art.

Nice to see you back here again

jkeny · Oct 28, 2012

This is an old but fascinating thread.
One question that Fas42 brought up rings through with me & I wonder if the MATT test has ever been used to evaluate if a change in electronics can produce different MATT results?

This discussion on intelligibility reminded me of a phenomena that I heard when only the electronics were changed in a playback system - from CD to computer audio. What I & others heard was on the first track of Shelby Lynn's "Just a little Lovin'" @47 seconds in (just before she starts singing) - on most systems this sounds like an extended bass note - this is actually resolved into 3 plucks of the bass in quick succession.

As I said nothing else in the room changed other than the front-end electronics, no speaker repositioning, etc. At the time I reckoned that it was greater resolution from the front end but failed to hear the same 3 bass string plucks on other systems using the same front end. Thinking now about it, the room obviously was also important to this increase in intelligibility.

I wonder could others listen to this Shelby Lynn track to check it's intelligibility @47 seconds in & maybe the MATT test can give a better correlation between measurements Vs audibility for electronics & not just room acoustics

NorthStar · Oct 28, 2012

jkeny said:
This is an old but fascinating thread.
One question that Fas42 brought up rings through with me & I wonder if the MATT test has ever been used to evaluate if a change in electronics can produce different MATT results?

This discussion on intelligibility reminded me of a phenomena that I heard when only the electronics were changed in a playback system - from CD to computer audio. What I & others heard was on the first track of Shelby Lynn's "Just a little Lovin'" @47 seconds in (just before she starts singing) - on most systems this sounds like an extended bass note - this is actually resolved into 3 plucks of the bass in quick succession.

As I said nothing else in the room changed other than the front-end electronics, no speaker repositioning, etc. At the time I reckoned that it was greater resolution from the front end but failed to hear the same 3 bass string plucks on other systems using the same front end. Thinking now about it, the room obviously was also important to this increase in intelligibility.

I wonder could others listen to this Shelby Lynn track to check it's intelligibility @47 seconds in & maybe the MATT test can give a better correlation between measurements Vs audibility for electronics & not just room acoustics

-----Hi John,

If you will allow me please; speaking of Frank (fas42), I just talked to him yesterday and the day before. ...He's doing just fine; he's happy, and surrounded by a good bunch of people.

That's all, TY. :b

Bests,
Bob

jkeny · Oct 28, 2012

NorthStar said:
-----Hi John,

If you will allow me please; speaking of Frank (fas42), I just talked to him yesterday and the day before. ...He's doing just fine; he's happy, and surrounded by a good bunch of people.

That's all, TY. :b

Bests,
Bob

I didn't know he was unwell - is he?

NorthStar · Oct 28, 2012

jkeny said:
I didn't know he was unwell - is he?

-----No no, Frank has been fine all along; it's just that he ain't with us no more that's all.
...Here at WBF.

jkeny · Oct 30, 2012

It's a pity that there isn't any further interest in this - I reckon we might be missing something by ignoring it.

Phelonious Ponk · Oct 30, 2012

NorthStar said:
-----Hi John,

If you will allow me please; speaking of Frank (fas42), I just talked to him yesterday and the day before. ...He's doing just fine; he's happy, and surrounded by a good bunch of people.

That's all, TY. :b

Bests,
Bob

Where is Frank? Virtually, that is.

Tim

Phelonious Ponk · Oct 30, 2012

jkeny said:
It's a pity that there isn't any further interest in this - I reckon we might be missing something by ignoring it.

I'd hardly call 16 pages ignoring it. I think it just ran it's course, John. Sometimes these things gain new life when they are brought back up like this. Maybe there's another 16 pages in it yet!

Tim

NorthStar · Oct 30, 2012

Phelonious Ponk said:
Where is Frank? Virtually, that is.

Tim

-----diyAudio

jkeny · Oct 30, 2012

Guys, don't get me wrong, I'm not hoping for Frank to reply

, I was just relating my experience & wondering if anyone has done any MATT tests or even given this Shelby Lynn track a listen? I know a lot of members here have this album "Just a little Lovin" & the track is the first one @ 47secs in. I would be interested in how many have rooms/systems that pass this intelligibility test at this frequency?

Anyone care to do the test? Takes about 1 minute to do

Phelonious Ponk · Oct 30, 2012

jkeny said:
Guys, don't get me wrong, I'm not hoping for Frank to reply , I was just relating my experience & wondering if anyone has done any MATT tests or even given this Shelby Lynn track a listen? I know a lot of members here have this album "Just a little Lovin" & the track is the first one @ 47secs in. I would be interested in how many have rooms/systems that pass this intelligibility test at this frequency?

Anyone care to do the test? Takes about 1 minute to do

Several of us took the intelligibility test and a few of those recorded their rooms for analysis. It's all documented in the early pages of this thread. I'm going to try your Shelby Lynn test tonight. I'll take any excuse to listen to that record...

Tim

jkeny · Oct 30, 2012

Phelonious Ponk said:
Several of us took the intelligibility test and a few of those recorded their rooms for analysis. It's all documented in the early pages of this thread.

Yes, Tim, I know. What I was hoping for was some who had scored well in room intelligibility could try changing their source for a less resolving source & do the test again - to see if it changed as Fas42 predicted & I suspect is correct. In other words, it might prove to be a useful measurement for analysing how resolving a device actually is (besides listening to it, that is

).It could help bridge the listening Vs measurements divide? I just don't know how sensitive the MATT test is?

I'm going to try your Shelby Lynn test tonight. I'll take any excuse to listen to that record...

Tim

Great! Look forward to your results.

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