What is your favorite house curve

[Floyd Toole]

If I understood your paper correctly, what's publicly known as Dr Toole curve (and I agree that's unfortunate and it's difficult to reach accurate information on the web especially in audio related subjects) is expected steady state response (radiated direct sound) of a speaker in a home theatre environment (small/reflective room) with a reasonably flat direct sound. What's publicly known as Harmon curve is the result of an experiment in which listeners adjusted bass and treble controls to achieve a satisfying spectral balance. I don't remember a specific volume level the test was run though and it can make all the difference in the perceived bass level which is probably coincidentally also the difference between these two curves.

The "Dr Toole" curve - please stop calling it that - is explained in my book as the average steady-state room curve, above the transition frequency at least, generated by loudspeakers that have received high sound quality ratings in double-blind tests over several decades of hundreds of tests. This identifies loudspeakers with the minimum resonant coloration - the most neutral - which is what we want as a starting point. Achieving such a curve in your room indicates that you MIGHT have purchased excellent loudspeakers. Compensating errors could also generate a nice looking curve, but not sound as neutral. Equalizing a flawed loudspeaker to create this curve, using it as a target, guarantees nothing - don't bother. But people do and fill pages of forums discussing the results - a social media exercise, not science.

The so-called "Harman" curve was a tone-control exercise which allowed listeners to play with broadband spectral trends (not normal resonances) to satisfy a preference for the particular programs being used. Young, inexperienced, listeners boosted bass and treble - but was it because they liked that result or was it because they wanted it louder. Unfortunately, we don't know from that test and further tests were not done. The starting loudness was a good foreground listening level, not a rock concert level or a chamber music level.

Being able to adjust bass level is essential for fussy listeners, but is not always available without frustrating layers of menus and momentary silences while digital adjustments are made. Old fashioned analog tone controls were truly useful. Small changes in bass level matter a lot.

 

[Floyd Toole]

Dr. Toole,
Thanks once again for stopping by our little hide-out for science oriented audiophiles.
If you have a minute I wonder if you could give me your thoughts on the below thoughts.
The gradual top end roll-off reflected in most published room curves may be fine for many - most.
But I'll be 74 and have lived an acustically hard life, LOL. What about the senior aged enthusiast (a large %)
who have already lost some level of hearing at the top?
I tend to first control the top end reverberation with room treatment.
Then aim for a flatter top end with EQ at the listening seat. ???
TIA,
Sal

Sorry, but it will not be rewarding to try to use spectral tweaks to compensate for serious hearing loss. Sometimes, the loss is obvious close to threshold, but less so at higher sound levels - it is called recruitment. Only trial and error will tell, and every person will be different. Good hearing aids are the best starting point, but finding them and getting them competently installed and set up might be a challenge. Good luck.

 

[DWPress]

Compensating errors could also generate a nice looking curve, but not sound as neutral. Equalizing a flawed loudspeaker to create this curve, using it as a target, guarantees nothing - don't bother.

Exactly! We try to explain this to people all the time here on ASR but it always digresses back to static curves because that is the easiest information for people to find and many DSP apps cater to this.

The video I posted above of fellow ASR member Joel has a click bait title but it goes into the science of why a static curve does not work for all speakers or rooms.

 

[Floyd Toole]

Thank you Dr. Toole for chiming in! I reference your book frequently though it may take several reads sometimes to get it into my thick head.

Not to distract from the current conversation but I found this video to have some good information:

Yes, some good information, mixed In with incomplete knowledge of the topic. Better than some, but still not the real story. He refers to my book - he needs to read it again.

 

[DWPress]

Incomplete knowledge - something we're all working on! But thanks again for your guidance, I'll pull your book back to bedside reading material to keep accumulating that knowledge.

 

[Newman]

Young, inexperienced, listeners boosted bass and treble - but was it because they liked that result or was it because they wanted it louder. Unfortunately, we don't know from that test and further tests were not done.

A great point. It would have been cool if the test had been designed with an automatic loudness compensation, such that when they dialled the bass or treble, the R128 loudness didn’t change.

 

[Newman]

Dr. Toole,
Thanks once again for stopping by our little hide-out for science oriented audiophiles.
If you have a minute I wonder if you could give me your thoughts on the below thoughts.
The gradual top end roll-off reflected in most published room curves may be fine for many - most.
But I'll be 74 and have lived an acustically hard life, LOL. What about the senior aged enthusiast (a large %)
who have already lost some level of hearing at the top?
I tend to first control the top end reverberation with room treatment.
Then aim for a flatter top end with EQ at the listening seat. ???

Hi Sal,

I have answered previous similar queries like this: as our hearing declines with age, we still listen to real live sounds (including voices and instruments, and every other natural sound), and our adaptive response sets this as our benchmark of what is real and natural.

So we will still assess deviations from that as unnatural.

Hearing aids are an example of this phenomenon. We need to keep them in, so that our adaptive response adjusts to them. Until then, they can seem very wrong and unbalanced.

 

[Floyd Toole]

Hi Sal,

I have answered previous similar queries like this: as our hearing declines with age, we still listen to real live sounds (including voices and instruments, and every other natural sound), and our adaptive response sets this as our benchmark of what is real and natural.

So we will still assess deviations from that as unnatural.

Hearing aids are an example of this phenomenon. We need to keep them in, so that our adaptive response adjusts to them. Until then, they can seem very wrong and unbalanced.

All true. No two humans have identical HRTFs, yet everything live or reproduced is heard through them. That means we start adapting to our individual peculiarities shortly after birth, and in many respects we continue through life, adapting to many things, including different acoustical listening spaces in real time. What we are finding is the limits of adaptation, so that we can focus on what is fixable.

A significant finding is that we adapt quickly to simple, mono sources in rooms and can identify small timbral defects in loudspeakers while "listening through" rooms. However, in stereo we are more forgiving of flawed loudspeakers, and in multichannel we are even more forgiving - we are less able to identify resonances in the loudspeakers, and by inference, in the source material as well.

It turns out that in stereo vs. mono tests using technical signals (pink noise and impulses) there is no difference in resonance detection - so what is going on? It appears that our clever hearing system loses its ability to adapt to listening room acoustics when the test material is commercial recordings all of which superimpose a layer of reflections not related to the listening room, but to a different, usually larger, real or synthesized space. That said, when a program contains a sustained mono component - a hard panned image - adaptation is possible, so it is still wise to select loudspeakers in mono tests, and enjoy them in multiple channel versions.

Adaptation is key to the listening experience - we are still learning.

 

[garyrc]

... I have noticed a tendency of many recordings to sound too "bright", at least brighter than I hear at live concerts and such, in many small rooms and that matches what I have read in various reviews and AES papers.

YMMV - Don

Yes, "too bright" is one of the likely problems with many CDs, less often with SACDs, and almost never with Blu-rays.

Recording studios and individual engineers / producers have different views of what "good balance" is, acoustics are different, monitor speakers are different, playback acoustics are different, what the suits think will sell is different.

It seems to me that the only solutions are:

1. High fidelity to the imagined original.
2. High fidelity to the desired original.
   
   

   I think the studios provide enough rolloff on top, and maybe a little too much cutoff on the bottom. You can't do much about missing lowend.

I do attempt to do something about missing low end. Here is an extreme example, for very, very bass shy recordings. It sounds much better.

 

[Sal1950]

Sorry, but it will not be rewarding to try to use spectral tweaks to compensate for serious hearing loss.

So we will still assess deviations from that as unnatural.

Good points guys, understood, thanks.
I wouldn't gauge my loss as "serious", mainly some rolloff on the top and a level of tinnitus hissing
that comes and goes at will. Most mainly do to a lifelong love of shooting firearms since my military days,
along with a lot of loud concerts and music playback in my younger times. Thankfully I grew aware of the loss
it was causing early on and got anally serious about using excellent protection before I turned 40.
When young, we don't cherish our sensory gifts as much as we should. I wonder if we shouldn't introduce some
education on the dangers to the kids. Maybe we do now ???

 

[JaMaSt]

so it is still wise to select loudspeakers in mono tests, and enjoy them in multiple channel versions.

In the mono testing you refer to, are you listening to music that has both the left and right channels blended together (using the term 'blended' for lack of a more technical term)?

 

[Floyd Toole]

All true. No two humans have identical HRTFs, yet everything live or reproduced is heard through them. That means we start adapting to our individual peculiarities shortly after birth, and in many respects we continue through life, adapting to many things, including different acoustical listening spaces in real time. What we are finding is the limits of adaptation, so that we can focus on what is fixable.

A significant finding is that we adapt quickly to simple, mono sources in rooms and can identify small timbral defects in loudspeakers while "listening through" rooms. However, in stereo we are more forgiving of flawed loudspeakers, and in multichannel we are even more forgiving - we are less able to identify resonances in the loudspeakers, and by inference, in the source material as well.

It turns out that in stereo vs. mono tests using technical signals (pink noise and impulses) there is no difference in resonance detection - so what is going on? It appears that our clever hearing system loses its ability to adapt to listening room acoustics when the test material is commercial recordings all of which superimpose a layer of reflections not related to the listening room, but to a different, usually larger, real of synthesized space. That said, when a program contains a sustained mono component - a hard panned image - adaptation is possible, so it is still wise to select loudspeakers in mono tests, and enjoy them in multiple channel versions.

Adaptation is key to the listening experience - we are still learning.

In the mono testing you refer to, are you listening to music that has both the left and right channels blended together (using the term 'blended' for lack of a more technical term)?

The key is to use a single loudspeaker. It doesn't matter whether what you are listening to is summed stereo, a single channel or an original mono. A single channel misses much of the music, so is less rewarding. The most revealing signal for resonances isn't music at all, but pink noise. Comparing more than two loudspeakers in equal loudness evaluations is very revealing of the differences between them because listeners have a chance to separate what is changing - the loudspeaker timbral signature - as separate from what is not changing: the room and the program.

 

[DonH56]

Nothing much to add but saw this thread had gotten lively again when I was tagged. I need to reschedule my long-overdue appointment with a calibrator to dial in my system, which @Floyd Toole 's post reminded me I have let slide. Also great to see Dr. Toole posting again, and hope you're enjoying the new place! I still greatly appreciate the time and advice you gave me some years back.

And of course this thread is another reminder that decades of experience can be dismissed in a few seconds on the 'net, and nobody wants to do the work to actually read and understand the research even when presented in an accessible way. I admit I am guilty of the latter as well...

 

[Keith_W]

For those who want some immediate gratification on Dr. Toole's views on target curves, download The Measurement and Calibration of Sound Reproducing Systems published in JAES 2015. While you are at it, you may as well hang around Linkwitz's website and read all the free stuff he has published.

 

[dlaloum]

So here is the challenge... knowing that the room response (AKA Target curve) is a consequence rather than a target

How does one leverage Dirac and/or Audyssey (or similar) to provide timbral matching of the speakers?

The low end is handled fine (whether boosted or not to taste) - but once we get beyond the schroeder frequency, there are benefits to be gained from using EQ to better match the voicing of surround/height vs main speakers.

I experimented early this year with measuring my mains, defining a target curve based on that response, and then applying it to the other speakers...

I later had to do a complete reset with an update to Dirac software, and new rear speakers - and this time I simply used the Dirac "handles" as they minimally change the overall voicing - results have been excellent, however, one does wonder whether better can be achieved (the curse of the audiophile...)!

In a perfect world, I would like to use EQ to match the direct anechoic response of the speakers (ie match their voicing), and then minimise other messing about (other than below the schroeder frequency)... and I would like to do this within the Dirac software interface... (ie: I don't want to be doing it all in the PC/Source... leave the EQ to the AVR!)

 

[Tim Link]

Yes, "too bright" is one of the likely problems with many CDs, less often with SACDs, and almost never with Blu-rays.

Recording studios and individual engineers / producers have different views of what "good balance" is, acoustics are different, monitor speakers are different, playback acoustics are different, what the suits think will sell is different.

It seems to me that the only solutions are:

1. High fidelity to the imagined original.
2. High fidelity to the desired original.

I do attempt to do something about missing low end. Here is an extreme example, for very, very bass shy recordings. It sounds much better.


View attachment 368620

I've given up chasing the individual recordings with EQ. I look for something that works pretty well with everything, and accept the recording for what it is. Nothing wrong with trying to do what you're doing though. I know it can really produce a more enjoyable listening experience sometimes. There are some recordings that strike me as really grating and I have tried to tame them, could not figure out how. My cousin just recommended Nick Cage's Abbatoir Blues and that first song Get Ready for Love makes me wonder if something might be seriously wrong with my system. It's supposed to sound like that? I think it is, because I like it sounding really distorted and stressed like it does.

 

[dlaloum]

I've given up chasing the individual recordings with EQ. I look for something that works pretty well with everything, and accept the recording for what it is. Nothing wrong with trying to do what you're doing though. I know it can really produce a more enjoyable listening experience sometimes.

My current AVR has Bass and Treble adjustment buttons on the remote... allowing for "instant" adjustments to taste...

I would prefer a Quad style "tilt" button - but old world bass and treble does the job fine! - salt & pepper to taste

 

[Keith_W]

So here is the challenge... knowing that the room response (AKA Target curve) is a consequence rather than a target

How does one leverage Dirac and/or Audyssey (or similar) to provide timbral matching of the speakers?

Can you tell Dirac and Audyssey not to perform corrections above a certain frequency range?

With Acourate, Focus Fidelity, and Audiolense you can perform different windowing for lower and upper frequencies. With very narrow windowing, you are effectively performing "broad tone controls" as Dr. Toole has recommended elsewhere. Or if desired, upper frequencies can be left out of the correction altogether. I would imagine that Dirac / Audyssey should have a similar function, it is a pretty basic feature.

 

[StigErik]

My current AVR has Bass and Treble adjustment buttons on the remote... allowing for "instant" adjustments to taste...

I would prefer a Quad style "tilt" button - but old world bass and treble does the job fine! - salt & pepper to taste

Same here. The treble adjustment on mine is very useful, and works like an old fashion analog tone control. It’s gives a high shelf @2500 Hz with Q = 0.7.

 

[Andysu]

Incomplete knowledge - something we're all working on! But thanks again for your guidance, I'll pull your book back to bedside reading material to keep accumulating that knowledge.

i keep Tom Holman beside for bedside reading , book is actually too scary to read