Where is the science in EQ of headphones?

[Aerith Gainsborough]

There’s nothing scientific about correcting to a preference curve which you don’t like.

Problem with your analysis:
I, and I am sure many others, do not know whether we like it or not until we hear it at least once.

Sure if I already heard it, it would be illogical to start from. Instead you start from the last target that you did like, if you have that data handy and adjust from there.

 

[GaryH]

The most scientific thing to do would be to correct to what the Harman research had before they asked people what they thought and gave them treble and bass controls to play with.

The closest you’ll get to that is pretty much Harman, but flat from 200 down to 20, instead of bass rising.

This is wrong, and a common misunderstanding of the research. I presume this stems from a misreading of this graph:

The black curve represents a good loudspeaker measured in a good room by the ear simulator of a HATS (without any headphone listener preference adjustments). Clearly, the bass is not visually flat. See Dr Sean Olive's post here.

The green curve is the response measured by the HATS of a loudspeaker EQed to have a flat in-room response (not a flat anechoic response), and so will sound sound bright, with deficient bass / excessive treble. This was only used as a convenient baseline curve in the subsequent bass / treble method of adjustment studies to find headphone listeners' preferred response in double-blind tests, shown by the blue curve, which likely has more bass than the black curve to perceptually compensate for the minimal tactile bass headphones provide compared to full-body bass felt from a large loudspeaker/subwoofer.

By the way, the Harman research doesn’t say that its curve is ‘what people like’. It says it’s an average of the people they measured. They also note that, when untrained listeners were removed, the average level of bass was lower.

Seems like another misunderstanding of the research. In their latest paper on this issue, Segmentation of Listeners Based on Their Preferred Headphone Sound Quality Profiles, Harman identify three main groups of preference:

Class 1: “Harman Target Lovers”
They make up the majority of listeners (64%) tested, and prefer neutral sounding headphones equalized to the Harman Target response curve. Membership includes an approximately equal balance of members across gender, age groups, and trained/untrained listeners. The exception is listeners over the age 50 who are more likely to be members of Class 3.

Class 2: “More Bass is Better”
This is the smallest class (15%) of listeners who prefer headphones with 3-6 dB more bass than the Target curve below 300 Hz. Members in this group are predominantly male, and include 30% of the trained listeners in our sample.

Class 3: “Less Bass is Better”
The second largest class (21%) prefers headphones with 2-4 dB less bass than the Harman Target curve below 100 Hz. Membership is comprised entirely of untrained listeners, and predominantly female and older listeners (50+ years).

So this means 70% of trained listeners preferred the Harman target, 30% preferred more bass than Harman, and none preferred less.

Also, I know a lot of people on here like to think they are when they're actually not, but the vast majority of people are not trained listeners, defined by Harman as passing all tests on level 8 or above of their How to Listen program and with normal audiometric hearing (no significant NIHL or presbycusis). If you do actually prefer (i.e. in blind, level-matched listening, not just casual sighted impressions prone to subconscious bias) less bass than Harman, and you are untrained (which the majority of people are), Harman's research shows you'll likely to be aged over 50, and the most probable explanation for this is age-induced hearing loss becomes significant at this time, which due to predominantly loss at high frequencies, relatively more treble / less bass will be preferred to compensate for this.

 

[Jimbob54]

Haven’t we been round this Harman loop before . Could we not just link to this ? https://audiosciencereview.com/forum/index.php?threads/headphones-and-the-harman-target-curve.17914/

It was a pretty rigorous airing of this whole debate .

 

[raistlin65]

Seems like everyone has a home brew for eq( enhancing ) headphones SQ on this forum. As a science based forum , the directive to just listen to changes does not get me very far. Once someone creates EQ adjustment list isn’t there an objective way to measure the suggested SQ improvements? The actions of amateurs and enthusiasts and electronics designers based on personal preferences does not instill a lot of confidence for me to try their various recipes. Why don’t headphone makers provide various EQ scenarios for their products? Just curious…

That is the problem. The very large majority of people that claim that their headphones sound better with a particular target have not done properly volume leveled, double blind testing.

Is there an expectation bias to like Crinacle's EQ curve because they like his reviews? Do they like the Harman target because they've been told that a majority of people do?

Maybe I'm wrong, but what I think we can say is that pretty much everyone benefits from correcting sharp peaks and dips to smooth the frequency response.

 

[Yorkshire Mouth]

This is wrong, and a common misunderstanding of the research. I presume this stems from a misreading of this graph:

View attachment 147136

The black curve represents a good loudspeaker measured in a good room by the ear simulator of a HATS (without any headphone listener preference adjustments). Clearly, the bass is not visually flat. See Dr Sean Olive's post here.

The green curve is the response measured by the HATS of a loudspeaker EQed to have a flat in-room response (not a flat anechoic response), and so will sound sound bright, with deficient bass / excessive treble. This was only used as a convenient baseline curve in the subsequent bass / treble method of adjustment studies to find headphone listeners' preferred response in double-blind tests, shown by the blue curve, which likely has more bass to perceptually compensate for the minimal tactile bass headphones provide compared to full-body bass felt from a large loudspeaker/subwoofer.



Seems like another misunderstanding of the research. In their latest paper on this issue, Segmentation of Listeners Based on Their Preferred Headphone Sound Quality Profiles, Harman identify three main groups of preference:


So this means 70% of trained listeners preferred the Harman target, 30% preferred more bass than Harman, and none preferred less.

Also, I know a lot of people on here like to think they are when they're actually not, but the vast majority of people are not trained listeners, defined by Harman as passing all tests on level 8 or above of their How to Listen program and with normal audiometric hearing (no significant NIHL or presbycusis). If you do actually prefer (i.e. in blind, level-matched listening, not just casual sighted impressions prone to subconscious bias) less bass than Harman, and you are untrained (which the majority of people are), Harman's research shows you'll likely to be aged over 50, and the most probable explanation for this is age-induced hearing loss becomes significant at this time, which due to predominantly loss at high frequencies, relatively more treble / less bass will be preferred to compensate for this.

Thanks for the input.

I’m 56.

I wonder what the age distribution curve is here.

I do find it strange that people not getting enough treble would compensate by turning down the bass, rather than turning up the treble.

 

[GaryH]

I do find it strange that people not getting enough treble would compensate by turning down the bass, rather than turning up the treble.

If you're referring to the bass/treble adjustment studies, the loudness was automatically normalized to the same level on adjustment, so turning down the bass would sound equivalent to to turning up the treble (not exactly the same, due to the different bass/treble filter shapes). It might be as simple as most listeners chose to adjust the bass first, resulting in both the bass and treble sounding about right (due to the loudness normalization), then adjusted the treble to fine-tune.

 

[Yuhasz01]

I still feel like EQ is like pouring ketchup on filet mignon…. Lot of compromising and adjustments , with tonality degradations , for the headphone. There should some scientific , objective criteria for doing this bit more measurable, than trust me give it a try….many many curves around web not just Harman, Amir or Oratory….

 

[someguyontheinternet]

I still feel like EQ is like pouring ketchup on filet mignon…. Lot of compromising and adjustments , with tonality degradations , for the headphone. There should some scientific , objective criteria for doing this bit more measurable, than trust me give it a try….many many curves around web not just Harman, Amir or Oratory….

Harman is based on statistical evidence. Most others are based on personal preference and/or subjective experiences.
The Harman target has a high chance of being the best or close to the best for the majority of people. That's why Amir uses it as the reference target.

The Harman target is based on statistical data on preference. That is a scientifically sound approach to this problem.

If you think that EQing to the Harman target degrades tonality, then you are among the few people whose personal preference is far from the Harman target.

 

[KeithPhantom]

To @Sean Olive, how does a speaker that measures flat in-room measure at the eardrum of a HATS with a standard artificial ear? I would love to see that curve.

 

[raistlin65]

If you think that EQing to the Harman target degrades tonality, then you are among the few people whose personal preference is far from the Harman target.

Not always. Sometimes people have headphones that don't respond well to EQing to HTR. Amir has found some of those.

 

[GaryH]

headphones that don't respond well to EQing to HTR

What do you mean by this?

 

[GaryH]

To @Sean Olive, how does a speaker that measures flat in-room measure at the eardrum of a HATS with a standard artificial ear? I would love to see that curve.

Scroll up to my earlier post. It's the dashed green curve on that graph. But as I explained there, this was only used as a convenient baseline curve in the subsequent bass / treble control headphone preference studies, and represents the sound of a bass-light, bright speaker (upwardly-sloping anechoic response), so I'm not sure what your interest in it is.

 

[dasdoing]

no curve will ever be cientific because your head is diferent from mine *.
the only way to realy make headphones neutral is by making a speaker (far from bounderies) flat in a very close nearfield. put your ear where the microfone was, and EQ the headphone to sound the same

*but Harman without bass boost is the most neutral in general, yes. the bass boost copies the bass boost in untreated listening rooms...this is not what neutral means

 

[KeithPhantom]

I'm not sure what your interest in it is.

Doing some research on it…

 

[raistlin65]

What do you mean by this?

Check out Amir's headphone reviews. Some headphones don't respond well to being EQed to HTR.

 

[KeithPhantom]

Check out Amir's headphone reviews. Some headphones don't respond well to being EQed to HTR.

This, subjectively, even using EQ settings from multiple people, my AirPods Max never sounded like Harman. They sounded recessed even when lifting the 1-5 kHz area. They never EQd like the measurements showed.

 

[maverickronin]

What do you mean by this?

Stuff like this.

This, subjectively, even using EQ settings from multiple people, my AirPods Max never sounded like Harman. They sounded recessed even when lifting the 1-5 kHz area. They never EQd like the measurements showed.

Who knows what it's DSP is doing unless your measurement chain lets you easily loop in EQ? And even that's assuming the DSP is static if you use conventional measurement techniques.

Besides that, passive headphones still have plenty of confounding factors. Bass distortion or low power handling can easily prevent you from using the full Harman bass shelf. Cancellation dips can cause unfixable nulls. It's also not uncommon for a headphone's treble to be full of narrow-ish Q peaks that can't be fixed without without killing all the treble because they shift too much with the position of the headphone on your head.

 

[Aerith Gainsborough]

I do find it strange that people not getting enough treble would compensate by turning down the bass, rather than turning up the treble.

Since I fall into that category: It's probably because we perceive the bass as overbearing while the treble is at a level we are used from real life.

What do you mean by this?

EG: EQing to Harman requires driver headroom the can doesn't have. The Result: increased distortion up to audible levels and thus obvious degradation of quality.

 

[Patrick1958]

I still feel like EQ is like pouring ketchup on filet mignon…. Lot of compromising and adjustments , with tonality degradations , for the headphone (speaker).

Replace headphone with speaker..... So why is it ok for speakers and not for headphones?

 

[Doodski]

There should some scientific , objective criteria for doing this bit more measurable, than trust me give it a try

I don't see what the issue is for you other than you think EQ ruins the sound quality. Have you tried using EQ?