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ASR Getting Into Measuring Headphones!

Robbo99999

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Please read the Harman AES papers.

What is measured at the microphones of the 45CA is the direct result of measurements and human subjects listening to "ideal" speakers in a "ideal" listening room.

Sure there are details in between and as you say it was not @amirm 's or my 45CA test fixture sitting in that room.

However what the 45CA microphones target is the Harmon Curve.

As I said, read the Harman AES papers for the details.

There is no "yes but"

Thanks DT

Note:
This was typed 11 hours ago. Now I press the reply button.
Oops
I'm not gonna unpick your post, but I will say that your second sentence doesn't even make sense and contains no logical/possible bridges within it.

Harman 2013 Headphone Curve: if you apply the slope of the Harman Speaker Curve to the dummy head eardrum measurement of in-room flat EQ'd speakers (from their papers) then it totally equals the Harman Headphone 2013 Curve, I know this because I've traced the curves in Virtuix CAD and applied the slope to it in REW - which is why I'd said in my previous post that "it's only the Harman Headphone 2013 Curve that has the bass levels & treble levels that would be seen as a direct measurement of a "Harman Curve Speaker" in a room" - which was to correct your original post to @Hayabusa. (Even if they supposedly came up with that Harman 2013 Curve by giving bass & treble controls to their test subjects - the fact remains re it being a direct & accurate reflection of applying the Harman Speaker Curve tilt to the dummy head eardrum measurement of in-room flat EQ'd speakers.) Now....the Harman Headphone 2018 Curve has more bass & treble, just as I said in my previous post, and I also know that was a result of their test subjects twiddling the bass & treble knobs.

You were also wrong to say/infer that it was a "Hammer Shaped" fixture (like Amir's) that was used in the creation of Target Curve - it wasn't, it was the dummy head (Kemar) version - which I corrected you on too earlier.

The only reason I replied to you earlier was to correct the mistakes you made in your original post to @Hayabusa. Please don't go tell me to read the papers, when you're making so many mistakes in your explanations/understanding.
 
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DualTriode

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I'm not gonna unpick your post, but I will say that your second sentence doesn't even make sense and contains no logical/possible bridges within it.

Harman 2013 Headphone Curve: if you apply the slope of the Harman Speaker Curve to the dummy head eardrum measurement of in-room flat EQ'd speakers (from their papers) then it totally equals the Harman Headphone 2013 Curve, I know this because I've traced the curves in Virtuix CAD and applied the slope to it in REW - which is why I'd said in my previous post that "it's only the Harman Headphone 2013 Curve that has the bass levels & treble levels that would be seen as a direct measurement of a "Harman Curve Speaker" in a room" - which was to correct your original post to @Hayabusa. (Even if they supposedly came up with that Harman 2013 Curve by giving bass & treble controls to their test subjects - the fact remains re it being a direct & accurate reflection of applying the Harman Speaker Curve tilt to the dummy head eardrum measurement of in-room flat EQ'd speakers.) Now....the Harman Headphone 2018 Curve has more bass & treble, just as I said in my previous post, and I also know that was a result of their test subjects twiddling the bass & treble knobs.

You were also wrong to say/infer that it was a "Hammer Shaped" fixture (like Amir's) that was used in the creation of Target Curve - it wasn't, it was the dummy head (Kemar) version - which I corrected you on too earlier.

The only reason I replied to you earlier was to correct the mistakes you made in your original post to @Hayabusa. Please don't go tell me to read the papers, when you're making so many mistakes in your explanations/understanding.

Okay Friend,

Just one more time around:

There was a Harman Standard listening room with Standard Spin-Orama calibrated Harmon speakers and a number of human subjects.

The speakers were played. The Human Subjects with the assistance of Harman Engineers put on headphones. The humans did some tweaks and adjustments. The tweaked headphones were measured on a GRAS 45CA test fixture. The PhD’s did some statistics and a few years later we have the current version of the Harman Curve.

The GRAS 45CA test fixture is the Industry Standard headphone measurement tool because Harman did the work and wrote the AES papers. The GRAS 45CA test fixture is the tool that they used.

There is no transfer function or correction curve that will allow or make any other measurement tool, including the KENMAR Head and Torso, equivalent.

Neither the KENMAR Head and Torso or the GRAS 45CA test fixture occupied seats in the Harman Standard listening room.

The GRAS 45CA test fixture was used to measure and document the headphones after the Human Subjects completed their preference adjustments.

The details are in the Harman AES papers.

Thanks DT
 

Robbo99999

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Okay Friend,

Just one more time around:

There was a Harman Standard listening room with Standard Spin-Orama calibrated Harmon speakers and a number of human subjects.

The speakers were played. The Human Subjects with the assistance of Harman Engineers put on headphones. The humans did some tweaks and adjustments. The tweaked headphones were measured on a GRAS 45CA test fixture. The PhD’s did some statistics and a few years later we have the current version of the Harman Curve.

The GRAS 45CA test fixture is the Industry Standard headphone measurement tool because Harman did the work and wrote the AES papers. The GRAS 45CA test fixture is the tool that they used.

There is no transfer function or correction curve that will allow or make any other measurement tool, including the KENMAR Head and Torso, equivalent.

Neither the KENMAR Head and Torso or the GRAS 45CA test fixture occupied seats in the Harman Standard listening room.

The GRAS 45CA test fixture was used to measure and document the headphones after the Human Subjects completed their preference adjustments.

The details are in the Harman AES papers.

Thanks DT
That's woefully inadequate/inaccurate as well as largely irrelevant. I'm not particularly interested in what your version of your understanding is of the Harman Process when it comes to the creation of their speaker & headphone curves, I was simply correcting the obvious mistakes you made in your explanation to another user, which I've already pointed out & explained in my prior posts.
 

DualTriode

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That's woefully inadequate/inaccurate as well as largely irrelevant. I'm not particularly interested in what your version of your understanding is of the Harman Process when it comes to the creation of their speaker & headphone curves, I was simply correcting the obvious mistakes you made in your explanation to another user, which I've already pointed out & explained in my prior posts.

So much bluster and so few facts. You want so much to be right.

Not for my benefit but for the others that are reading here, show us Published Harman AES documentation that the KENMAR mannequin was used in the development of the Harman curve.

Until then you are blowing smoke up our skirts.



Thanks DT
 

Robbo99999

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Firstly, @DualTriode , you're getting things out of perspective. The track of the conversation was as follows, you replied to Hayabusa's post below with your post that I include below it.
Hi Amir, I was just thinking about thia experiment: It would be nice to see what the transfer function of the 45CA-10 is if the source would be from a set of speakers setup in a typical stereo setup/listening distance.
This could be done by using the speakers as source and then measure the difference between the FR with the 45CA-10 and a calibrated mic at the same position.
This should give some kind of inverse version of the Harman curve isn't it?

Hello,

This is exactly what Harman's, Sean Olive PhD, did as documented in the AES papers.

It is exactly the Harman Curve.

Secondly, I reply to your post above pointing out your (mistakes)/innacuracies in your response here - I'm sure you'd admit they were innaccurate:
And then I further expand on my points in a later post.

I'm not interested in fleshing out all the details of how the Harman Headphone Curve was created with you now, but I can see you have some points wrong, and my initial points I made to you in my first posts were showing the most obvious mistakes you made. If it was earlier in the day, and you weren't you and being your obtuse self in your first reply to me then I might have bothered to go into more detail. You can think what you like about it. I will admit that I've not read the AES Papers, but I've seen important snippets from them that certain knowledgeable ASR members have posted, as well as Harman Slide shows from Sean Olive on the topics, so I know enough to have pieced it together in terms of how the Harman Headphone Curves were created, and enough to know you made mistakes in your explanations to Hayabusa, and also a few points in your subsequent posts. I'm not going into the whole Harman process in depth with you now. As I said, I pointed out your most obvious mistakes in my first post I replied to you at the beginning of this now ridiculous exchange.
 
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ADU

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There is no transfer function or correction curve that will allow or make any other measurement tool, including the KENMAR Head and Torso, equivalent.

Diffuse field + diffuse sound power looks pretty good, DualTriode. We need more in-ear measurements of speakers to confirm this though, and to improve the precision of Harman's in-ear response curve.
 
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DualTriode

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Firstly, @DualTriode , you're getting things out of perspective. The track of the conversation was as follows, you replied to Hayabusa's post below with your post that I include below it.




Secondly, I reply to your post above pointing out your (mistakes)/innacuracies in your response here - I'm sure you'd admit they were innaccurate:
And then I further expand on my points in a later post.

I'm not interested in fleshing out all the details of how the Harman Headphone Curve was created with you now, but I can see you have some points wrong, and my initial points I made to you in my first posts were showing the most obvious mistakes you made. If it was earlier in the day, and you weren't you and being your obtuse self in your first reply to me then I might have bothered to go into more detail. You can think what you like about it. I will admit that I've not read the AES Papers, but I've seen important snippets from them that certain knowledgeable ASR members have posted, as well as Harman Slide shows from Sean Olive on the topics, so I know enough to have pieced it together in terms of how the Harman Headphone Curves were created, and enough to know you made mistakes in your explanations to Hayabusa, and also a few points in your subsequent posts. I'm not going into the whole Harman process in depth with you now. As I said, I pointed out your most obvious mistakes in my first post I replied to you at the beginning of this now ridiculous exchange.
Hello,

It has been a couple of days. You have presented no evidence that the KENMAR mannequin had any role in developing the Harman curve for headphones.
So you statement about the KENMAR mannequin is more bluster than fact.

The Harman Cruve is statistically derived from the responses of a number of human subjects. The PhD's rendered a equalization curve from the data that is right down the center of 68% of the human subjects tested. Not quite a perfect match for everyone.

This is really very good shooting to reach plus minus 1 Standard Deviation of the population. If I was a manufacturer of headphones 68% is a remarkable work.

At this point AKG (a Harman company) took the K712Pro headphone, a not to expensive high quality headphone and created some software to equalize the AKG K712 to the Harman Curve or the Frequency Response of most any other headphone on the market at the time.

The GRAS 45CA is the Lab tool to measure the headphones after the Human Subjects finished their preference adjustments

I went out and purchased a Gras 45CA and several different headphones including the AKG K712 and LCD2.

The LCD2 turned out to be my favorite headphone for equalizing to any Frequency Response curve that I wanted.

See the attached measurements of the K712PRO and LCD2 headphones

K712ProLevel and Distortion.png
Level and Distortion.PNG

The above test plots do not have the Harman Curve superimposed.

Diffuse field + diffuse sound power looks pretty good, DualTriode. We need more in-ear measurements of speakers to confirm this though, and to improve the precision of Harman's in-ear response curve.

Hello,

I do not know that Harman has made any in ear Diffuse field + diffuse sound power measurements or a Harman in-ear response curve. At least not as part of the development of the Harman Curve.

Please tell us more about what you are thinking.

Thanks DT
 

ADU

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Hello,

I do not know that Harman has made any in ear Diffuse field + diffuse sound power measurements or a Harman in-ear response curve. At least not as part of the development of the Harman Curve.

Please tell us more about what you are thinking.

Thanks DT

Sure. I've already tried to explain this in a few other topics here. But I guess one more can't hurt. :) The cliffs notes version of DF+SP goes somethin like this...

A headphone will have a neutral response if its diffuse field compensated response roughly approximates the average overall shape of a neutral loudspeaker's diffuse sound power response. This seems to work especially well with headphone measurements made on some of the newer HATS measurement rigs, like the HBK 5128.

Harman has generally been rather dismissive of concepts based on a diffuse field for headphones. But they used a very similar idea to the one above to create early versions of their target headphone response curve, when they EQ'd some speakers to a completely flat response in their reference listening room, and then measured the in-ear response of that arrangement using some type of mannikin or dummy head. And then combined that with their preferred in-room loudspeaker curve (or PIRL) at the time.

The room that Harman used for their in-ear measurements was probably not a true diffuse sound field, with equal intensity in all directions. But the concept they were working with was very similar.

You cannot use the diffuse field measurement of a HATS rig as a neutral target just by itself, because it will be too brightly tilted towards the treble. If you combine it with something close to the average sound power of a neutral loudspeaker though, then it should be fairly close to a neutral response, imo. YMMV of course.
 
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Robbo99999

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Hello,

It has been a couple of days. You have presented no evidence that the KENMAR mannequin had any role in developing the Harman curve for headphones.
So you statement about the KENMAR mannequin is more bluster than fact.

The Harman Cruve is statistically derived from the responses of a number of human subjects. The PhD's rendered a equalization curve from the data that is right down the center of 68% of the human subjects tested. Not quite a perfect match for everyone.

This is really very good shooting to reach plus minus 1 Standard Deviation of the population. If I was a manufacturer of headphones 68% is a remarkable work.

At this point AKG (a Harman company) took the K712Pro headphone, a not to expensive high quality headphone and created some software to equalize the AKG K712 to the Harman Curve or the Frequency Response of most any other headphone on the market at the time.

The GRAS 45CA is the Lab tool to measure the headphones after the Human Subjects finished their preference adjustments

I went out and purchased a Gras 45CA and several different headphones including the AKG K712 and LCD2.

The LCD2 turned out to be my favorite headphone for equalizing to any Frequency Response curve that I wanted.

See the attached measurements of the K712PRO and LCD2 headphones

View attachment 236067View attachment 236068
The above test plots do not have the Harman Curve superimposed.



Hello,

I do not know that Harman has made any in ear Diffuse field + diffuse sound power measurements or a Harman in-ear response curve. At least not as part of the development of the Harman Curve.

Please tell us more about what you are thinking.

Thanks DT
Harman did use a mannequin head as one of the starting points to derive the Target Curve:
Harman Step 3.jpg


And for other people the run down of the whole process of how the Harman Headphone Curve was created with some simple slides from Harman (from start to finish sequentially Step 1-4):
Harman Step 1.jpg Harman Step 2.jpg Harman Step 3.jpg Harman Step 4.jpg
to add some clarification, step 4 is when they gave the headphone to their subjects and asked them to twiddle bass & treble knobs to arrive at their most preferred sound on a variety of tracks, and then Harman looked at that data to apply the generally most preferred bass & treble levels to the original baseline dummy head measurement from Step 3 in order to arrive at their final target curve (the Harman Headphone Curve).
 
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