Not sure I like Harman curve

[KeithPhantom]

Harman curve, a target developed based on preference of various test listeners and their input of an in-room flat speaker and how it would be reflected in an over-ear headphone. I do understand why some may not like, not everyone falls in the expected confidence interval of a study, and that’s to be expected in any study.

For a headphone to be successfully equalized to something close to this curve it needs to have a few characteristics:

1. A low distortion profile across the listening frequency range.
2. Good unit-to-unit frequency response compliance.
3. As few high Q (low? bandwidth) imperfections as possible.
4. Good channel tracking.
5. Enough power to drive a possible bass boost.

Developing a curve for this kind of headphone will yield the best results. I discovered all of this while researching the best headphone to equalize to this curve, and these issues ruined the final curve. But when I found my current headphone (Sennheiser HD 560S) and applied the curve, it was a complete eye-opener personally.

Another thing is that I do not use presets, both Oratory’s and AutoEQ’s presents are not straight Harman OE. They both sound different to each other, and most of the time, bad to my ears. Oratory uses ear tuning when developing his results and AutoEQ uses some variation of Harman, but with a different bass boost profile. I do use the actual AutoEQ program, but input the straight Harman curve (2018 OE) as the target, and that curve just sounds great and “right” when comparing it to the best speakers in treated rooms I’ve heard in my life. It literally transformed my 560S into a combination of the best aspects of all headphones I’ve owned (almost same soundstage as HD 800 and the same detail retrieval, almost same bass as LCD series, same “dynamic range” as Focals, and still as flat in thr midrange as the HD 600 without the lack of bass [aubjecitve]).

 

[Chromatischism]

AKG K712s have been my headphones for many years. I love the spacious sound and comfort.

I've been back and worth with the EQ from the review thread.

I feel that the EQ makes the sound very dull. The airiness that I love about these headphones is gone. It just comes a very boring headphones to listen to.

I'm just not used to neutral. And not sure that I want it.

It doesn't look like anyone has asked this (very important) question yet:

How was the EQ applied?

 

[MayaTlab]

1. A low distortion profile across the listening frequency range.
2. Good unit-to-unit frequency response compliance.
3. As few high Q (low? bandwidth) imperfections as possible.
4. Good channel tracking.
5. Enough power to drive a possible bass boost.

And translate well from how it measures on an ear simulator to how it performs on your own head .
This is so susceptible to leakage and variation across individuals that how it measures on an ear simulator is for all intents and purposes basically immaterial :

Headphones v1.3.1 - Graph Tool

www.rtings.com

 

[KeithPhantom]

And translate well from how it measures on an ear simulator to how it performs on your own head .
This is so susceptible to leakage and variation across individuals that how it measures on an ear simulator is for all intents and purposes basically immaterial :

Headphones v1.3.1 - Graph Tool

www.rtings.com

Yes, this as well. Finding a good headphone that is a good representation (after equalization) of the Harman target is harder than many think. I spent months in the process, and I determined that the best choices are headphones already close the Harman target when stock.

I still think that the sample size was pretty small for the study and I would love to see more studies being done considering both the physical and psychologically aspects of our interpretation of hearing and how it relates to the many ways we listen to music.

 

[captainbeefheart]

BTW, If Harman is the way of the future why do we get so upset about DAC filters that cut off at 19k instead of 20k. There is nothing to hear anyway, equalising to a Harmon curve starts to kill everything above 15k!

I always remembered a reference by Toole (I think, don't quote me) that for high quality sound reproduction the system should reach at least 13khz and speakers sound dull if they don't reach up to 13kHz. I'll try and find the exact reference and context to what he was talking about but that jives with the Harman curve and the roll-off above 15kHz.

I'm personally sensitive to high frequencies and if a high bandwidth amplifier is partially unstable and shows high frequency anomalies (distortion, ringing/overshoot) I get fatigued and can't enjoy the music.

 

[MayaTlab]

I still think that the sample size was pretty small for the study

Which one in particular ?
The 2018 article for over-ears (https://www.aes.org/e-lib/browse.cfm?elib=19436) pitted the target against 31 other alternative curves, and involved 130 listeners.

Yes, this as well. Finding a good headphone that is a good representation (after equalization) of the Harman target is harder than many think. I spent months in the process, and I determined that the best choices are headphones already close the Harman target when stock.

If I use averages of on-head measurements as a way to guesstimate what the target is meant to sound / measure (in situ) like (ex here : https://audiosciencereview.com/foru...ctivist-bang-for-your-buck.34596/post-1207611) - not necessarily the most most foolproof methodology anyway, the ones that come closest to them after EQ, using third party presets created from measurements of different samples, rarely are the ones that already came closest to the target, without EQ, on an ear simulator.

The K371 and N700NCM2, for example, aren't a particularly good match for any of these rough estimates. To be fair no single individual pair of headphones match them well anyway, but these two are quite frankly off.

That little experiment of mine though most definitely suffers from a small sample size, let alone methodological pitfalls !

 

[Sokel]

Just for a quick test with Audeze LCD X EQ'd with HC curve (not my taste by the way) about the audibility of >10K Hz with the below is still clear as a sense.
I don't think the curve kills as much as we think.

https://audiosciencereview.com/foru...sl-do100-review-stereo-dac.34198/post-1194714

 

[Soandso]

I would love to see more studies being done considering both the physical and psychologically aspects of our interpretation of hearing and how it relates to the many ways we listen to music.

KeithPhantom, - Among several brain auditory pathway components the following may interest you.

The superior olivary complex deals with coordinating what we hear from both left and right ears. Thus placing sound by using the time of sound arrival and respective sound levels at each ear.

In the brain thalamus the medial geniculate body is comprised of sectors. It's ventral sector modulates frequency spectrum and time information into formats for various neural pathways reaching not only auditory components, but also the brain amygdala and some of our other senses' wiring.

The medial geniculate body link to our amygdala makes sound potentially pleasurable/sad or an alert of concern. The amygdala enhances "...attention and associated perceptual encoding of emotional events, and thereby increases their subjective salience .... [It]... generates affective experience ...." [Quote: doi:10.1093/scan/nsm022 ]

The inferior colliculus coordinates neural impulses between several sectors in the brainstem. Such as the lemniscal central nucleus which is involved with, among other things, processing sound frequency spectrum in the context of time information of that sound. While it's dorsal sectors deal with sound feedback processing and it's lateral sectors deal with integrating input from multiple senses, including auditory.

 

[JJB70]

At the end of the day preference is preference, when it comes to talking about bass it's like asking someone how much salt to add when cooking. Some people find food tasteless without salt, some find salt over powers all the other flavours. You like what you like and I see nothing wrong with that. If people like Beats bass canons then good luck to them, I like the Etymotic studio response tuning, I know some find it dry and boring but I find Harman is bass heavy for my taste.

 

[tomtrp]

I played around with peq with data from asr, oratory, crinacle, autoeq a lot with a lot of expensive or cheap headphones. (I tried tuning on hd800, hd800s, hd6xx, hd600, hifiman sundara, arya, he1000v2, he6sev2, Ananda, beyerdynamic t1 first gen, dt990, T90, DT1990, focal utopia, focal clear, focal elex, th900mk2, audeze lcd XC 2021, goldplanar GL2000 double magnet.)
1. Harman Target bass is not a fixed standard by its nature. You are free to adjust the bass to the level you like since the bass level is adjusted to the preference of the test group under certain test recordings. Your own preference and the recording quality of your music collection can shift the bass boost level. For myself only, the Harman 2013 bass or the 70 phon bass sounds more close to genelec 8351b in a treated room.
2. The target is highly smoothed out. Certain deviations from the Target after 5khz that can correctly reflect the difference between your own ear and the ear on the test rig can definitely improve the sound further. It is not necesaary to mechanically PEQ the FR to exactly match the Target, even Amir will not do that.
If you really want to pursue the most neutral sound possible, you may need to buy a good pair of speakers like 8351b and do some room correction with REW and then use Harman Target as a starting point only, fine tune the FR after 5khz(even after 1khz) to find the sound that mimics the reference speaker OR just tune the sound that sounds best to your ears.
This may be time consuming. As developing proper high frequency filters that deviates from the Target needs careful treatment. For example, be careful about high Q filters, it can make the FR curve more peaky if you place it in the wrong place.
A deviation that is always worth trying is to create a small dip around 7khz like many many good sounding headphones do. This makes the sound less sibilant and cleaner if the headphone already has enough level after 8khz.

 

[pitseleh]

I do use the actual AutoEQ program, but input the straight Harman curve (2018 OE) as the target, and that curve just sounds great and “right” when comparing it to the best speakers in treated rooms I’ve heard in my life. It literally transformed my 560S into a combination of the best aspects of all headphones I’ve owned (almost same soundstage as HD 800 and the same detail retrieval, almost same bass as LCD series, same “dynamic range” as Focals, and still as flat in thr midrange as the HD 600 without the lack of bass [aubjecitve]).

Would you mind sharing the EQ you use?

 

[KeithPhantom]

Would you mind sharing the EQ you use?

Preamp: -6.3 dB
Filter 1: ON PK Fc 22 Hz Gain 6.0 dB Q 0.67
Filter 2: ON PK Fc 73 Hz Gain 1.5 dB Q 2.21
Filter 3: ON PK Fc 194 Hz Gain -1.2 dB Q 1.13
Filter 4: ON PK Fc 1238 Hz Gain -3.8 dB Q 1.40
Filter 5: ON PK Fc 1918 Hz Gain 2.8 dB Q 0.48
Filter 6: ON PK Fc 3128 Hz Gain -2.0 dB Q 4.77
Filter 7: ON PK Fc 4770 Hz Gain -4.6 dB Q 2.60
Filter 8: ON PK Fc 9606 Hz Gain 5.3 dB Q 1.89

 

[Cars-N-Cans]

Developing a curve for this kind of headphone will yield the best results. I discovered all of this while researching the best headphone to equalize to this curve, and these issues ruined the final curve. But when I found my current headphone (Sennheiser HD 560S) and applied the curve, it was a complete eye-opener personally.

How has the HD 560S held up so far? I went back to revisit my Sundara headphones due to the subject at hand and it’s clear there is nothing left to EQ. Compared to my IEMs and speakers they are now somewhat dull and harsh with resonances. Listening to dialog on them is almost unbearable at times now. I thought this was my imagination but it was not. They did sound fantastic initially on the Harman curve, but I think the extra bass boost combined with bass heavy content at high volumes caused the membranes to loose tension. No post mortem yet, but I suspect all that’s left to do is grab a fork at this point. I did put an order in for the 560S myself. Hopefully I can make these last longer by not being overzealous with the volume. That was one thing I did not consider was whether the headphone can tolerate the extra low frequency energy.

 

[pitseleh]

Preamp: -6.3 dB
Filter 1: ON PK Fc 22 Hz Gain 6.0 dB Q 0.67
Filter 2: ON PK Fc 73 Hz Gain 1.5 dB Q 2.21
Filter 3: ON PK Fc 194 Hz Gain -1.2 dB Q 1.13
Filter 4: ON PK Fc 1238 Hz Gain -3.8 dB Q 1.40
Filter 5: ON PK Fc 1918 Hz Gain 2.8 dB Q 0.48
Filter 6: ON PK Fc 3128 Hz Gain -2.0 dB Q 4.77
Filter 7: ON PK Fc 4770 Hz Gain -4.6 dB Q 2.60
Filter 8: ON PK Fc 9606 Hz Gain 5.3 dB Q 1.89

Thanks. After listening to a few tracks, I think I get better instrument separation than with Oratory’s settings. Will spend some more time with these.

 

[Soandso]

Sound frequencies are, at one stage, processed in our brain via different neurological connections with orientation ( "tonotropic") for a certain frequency. In other words low and high frequencies do not linearly similar localize into our auditory neural circuitries.

As auditory information progresses along the neurons with frequency response specificity in the Heschel gyrus has correspondingly frequency specific neurons in the immediately nearby neurons. In the (top to bottom & front to back) layers of these neural clusters the neurons exhibiting inherent patterns of frequency preferences spatially reorientate - presumably for specialized connectivity to further auditory pathways.

What must be understood is that in some of us human anatomy varies so that not everyone had just one Herschel gyrus in each side (left and right) of our brain. There can be up to three (3) Herschel gyrus on each side and even variations of the number of Herschel gyrus between the left snd right.

Even among people with the common pair of Herschel gyrus the actual pattern of frequency preferences seem to map out different for one's own left and right gyrus. I haven't seen any published images showing consistently that the left side or the right side Herschel gyrus has a preponderance of responding better to either a high or low frequency.

 

[Soandso]

Here are examples from six individuals' brain patterns of where they localize responses for specific sound frequencies. We apparently vary being relatively more tuned to different sound frequencies. To interpret the tonotopic organization color shading running from red to blue representing distinct frequencies see the scale at the bottom of the image pictures. [Note: there are other published reports using different imaging techniques showing other examples of human variation in frequency tonotropic organization.]

 

[ADU]

I have reservations about how people may apply EQ to speakers/headphones. My impression is the accepted initial step is to microphone measure the different transduced frequencies and then, based on that data pattern, make EQ adjustments (such as those based on the Harman curve, or guidelines for certain kinds of music).

What my left and right aged ears' testing revealed is there are differences how loud (dB) specific frequencies are being heard, but also differences in the pattern of loudness being heard at said frequencies. In other words: in frequencies that are heard at worse than the clinical norm (25dB) the extra dB needed to hear that specific frequency is not always the same for left and right ears.

Then too, among the frequencies where hearing is less than normal the dB required to hear those frequencies does not follow the same pattern in both left and right ears. In one ear the trend of relative decline of frequency hearing does not occur in one ear at 1 kHz, yet for the same 1 kHz frequency in the other ear there is hearing decline.

And furthermore, even though the general trend of worse hearing is occurring in both ears at 2kHz in one ear at subsequent higher frequencies my impaired hearing is still better than it is at 2kHz in the other ear; and hearing falls from there in a pattern of decline at yet higher frequencies. To further demonstrate variability: in one ear there is a different subsequent higher frequency of those beyond 2kHz where I hear better than what that ear's 2kHz pattern of impairment is.

EQ adjustments based on microphone readings with the end goal of giving one a desired sound spectrum seems to be relevant for those with perfect hearing. We can EQ from those readings and yet not be on target if one ear has limited hearing of several specific frequencies at different base-line dB, nor on target for the other ear if it, in turn, has limited hearing of a different set of specific frequencies at different base-line dB.

Hearing loss is evidently different than the Fletcher-Munson "equal loudness" curve. Although clinical evaluation of hearing loss is usually only done from 25Hz to 8kHz the isolation of frequencies tested rules out any artifacts of masking. If you are 65 years of age or older treat the balance dial as your friend and consider whether EQ-ing to personal taste by ear may be preferable to EQ-ing from measurements.

I believe that most of the participants in Harman's preference research were tested for normal hearing. So correcting or compensating for different levels or types of hearing loss was probably not one of the primary goals of either their research, or research into the subject of equal loudness (which is a different, but related topic).

The Harman studies seemed to reveal some differences in preference between different demographic groups though, that were possibly related to age, sex, and other factors. Young males had slightly different preferences than older males for example. And I believe there were also some differences based on gender.

I don't think there were any direct connections made to hearing loss. But indirect relationships seem to be strongly implied by some of their results. Older men tend to suffer from more upper midrange hearing loss, for example. And this seems to correlate with some of their sound preferences versus the younger males.

Some older men (and women?) also suffer from something called hidden hearing loss, or HHL, which could also influence their preference for less room reflections when listening to speakers. And maybe also brighter-sounding headphones, where there's potentially less masking of the higher frequencies by the bass or lower frequencies. The former is briefly discussed by Floyd Toole in the 2nd page of this article...

Room Reflections & Human Adaptation for Small Room Acoustics

Dealing with acoustics in small rooms is no trivial matter. This article focuses on how to treat early reflections based on listening habits, your loudspeaker choice. Absorb, diffuse, reflect; decide.

www.audioholics.com

Room Reflections & Human Adaptation for Small Room Acoustics

Dealing with acoustics in small rooms is no trivial matter. This article focuses on how to treat early reflections based on listening habits, your loudspeaker choice. Absorb, diffuse, reflect; decide.

www.audioholics.com

 

[ADU]

Sound frequencies are, at one stage, processed in our brain via different neurological connections with orientation ( "tonotropic") for a certain frequency. In other words low and high frequencies do not linearly similar localize into our auditory neural circuitries.

As auditory information progresses along the neurons with frequency response specificity in the Heschel gyrus has correspondingly frequency specific neurons in the immediately nearby neurons. In the (top to bottom & front to back) layers of these neural clusters the neurons exhibiting inherent patterns of frequency preferences spatially reorientate - presumably for specialized connectivity to further auditory pathways.

What must be understood is that in some of us human anatomy varies so that not everyone had just one Herschel gyrus in each side (left and right) of our brain. There can be up to three (3) Herschel gyrus on each side and even variations of the number of Herschel gyrus between the left snd right.

Even among people with the common pair of Herschel gyrus the actual pattern of frequency preferences seem to map out different for one's own left and right gyrus. I haven't seen any published images showing consistently that the left side or the right side Herschel gyrus has a preponderance of responding better to either a high or low frequency.

Here are examples from six individuals' brain patterns of where they localize responses for specific sound frequencies. We apparently vary being relatively more tuned to different sound frequencies. To interpret the tonotopic organization color shading running from red to blue representing distinct frequencies see the scale at the bottom of the image pictures. [Note: there are other published reports using different imaging techniques showing other examples of human variation in frequency tonotropic organization.]
View attachment 213722

If you want to use preference as the basis for your EQ adjustment or FR assessments, there are many dark rabbit holes that can potentially take you down. This is why I try to focus most of my attention on differences in response which can be a bit more easily seen/identified, measured/quantified, and compared on an FR graph.

I also suffer from hearing loss, for example. But have little or no interest in trying to adjust the sound of my headphones to compensate for that, in part because I'm afraid that doing so might actually help to accelerate the degradation in my hearing.

Achieving something close to the measured in-ear response of neutral loudspeakers in a room is sufficient for me. That is challenging enough. And imho, the Harman curve doesn't really go far enough towards accurately approximating this, particularly in the upper frequencies.

The only other tweaks I'd generally apply are to compensate for differences in volume (which is what Fletcher-Munson/equal loudness is about). Or maybe simulating some different types of speakers, or room sizes/conditions. But that's about it. There's alot of room for variation and different adjustments or sound signatures within the scope of just those parameters though.

 

[Soandso]

ADU, - As regards hidden hearing loss: this is clinically about speech hearing difficulties when there is noise. It is also referred to as noise induced hidden hearing loss.

Sound signals promulgate via the auditory nerve after a neurotransmitter (glutamate) goes into a synapse. Those synapses links our ears' inner hair cells to the auditory nerve fibers ascending (afferent) into our brain.

It seems we have distinct types of those afferent auditory nerve fibers (apparently evolution made it so that all of these are meant to be always "on" - firing somewhat even when we have no incoming sound). The important point here is that 10-16% of these fibers have an exceptionally low rate of firing (less than 1/2 spikes/second) relative to the other two (2) sub-types of auditory fibers staged there (on the other side of synapses) which fire at higher rates.

It is precisely these low rate firing auditory nerve fibers which are integral to getting speech processed onwards when there is concurrent noise. Human exposure to very loud noise can cause specific problems (the inner hair cells don't de-polarize properly and so only get selective glutamate release) at particular synapses linking the ears' inner hair cells and the above described sub-type of 10-16% nerve fibers ascending into our brain.

 

[Lunafag]

Don't use presets above 5k. Here's my EQ for example, the graph shows a peak at 8k but when I do a sine sweep there's actually a dip there, which the preset would have only made worse. And the graph shows nothing special at 10k but there's actually a peak there. Another important thing to do when comparing EQ/no EQ is to volume match them.