Harman preference curve for headphones - am I the only one that doesn't like this curve?

[ZolaIII]

Yes this is essentially it. The hypothesis is that recordings are made to sound good through loudspeakers in rooms so try to emulate at least the spectral balance of the experience through headphones. We started by acoustically measuring a loudspeaker in a room through an ear simulator/head and from there slightly tweaked the bass.

Why tweak the bass? Because there is not a 1:1 relationship between bass heard in a room through loudspeakers and via a headphone. We discovered this years ago when doing binaural reproduction of car audio systems through headphones to do controlled double blind A/B tests of different car audio systems. When you compare the headphone experience with the car speakers there was some missing bass. We measured the wholebody vibration in the car and found that the missing tactile experience in the headphones was equivalent to 2-3 db bass

http://www.aes.org/e-lib/browse.cfm?elib=15150

Of course there will be a difference between bass reproduced on a loudspeakers which can't go that low, have much higher distortion there and who's energy in that area fades fast with distance. So reproduction of recorded materials (on speakers) which were reproduced later on hedaphones would actually sound bad as it's not a same thing (speakers and hedaphones) to start with. You got only 2~3 dB as it whose in small spece (car) it would be bigger as distance from speaker increase.
https://github.com/jaakkopasanen/AutoEq/blob/master/compensation/loudspeaker_in-room_flat_2013.png
But certainly no one will do that.
Still this wouldn't translate to fat dB + from 0 dB in that region. Actually as I am sure that you already know there are hedaphones tuned to recreate behaviour of speakers more closely. Which is something I prefer to call traditional Japanese tuning (date's back to Onkyo Institute day's) with slight push down on complete bass region with additional roll off as 70 Hz (also less emphasised hump in high mids and onwards). Which whose well i guess most part OK for traditional dynamic driver's, beats me why they still do it with drivers which actually can go much lower (even under 20 Hz). For instance Fostex planars. Probably because they live convinced that they need to sound as speakers. For me heaphones are hedaphones and should be let to do what they can. Cuting it down is plane wrong diminishing fidelity and adding things which shouldn't be there in the first place is what we commonly call distortion. There for your starting hypothesis whose wrong (at least regarding proper recorded materials) and so whose assumption behind it that hedaphones should sound as speakers as they (hedaphones) can do more.

 

[PH73]

Not Sean (obviously!), but I would have thought this was fairly uncomplicated: speakers in a room sound like everyhing else in a room, i.e. natural to our evolved sense of 'what stuff sounds like' in a room. We thus want our headphones to sound similar. As far as I can tell, this is exactly what the Harman headphone curve achieves - a gently downward sloping even response from 20Hz - 20 kHz ...

Maybe I am overcomplicating this! There is something appealing about having 'flat' or accurate at some part of the process. For speakers it has been shown that it is flat anechoic on axis/ listening window that should be the target. A downward sloping room curve is the consequence of that rather than a target in itself. The slope will be related to the directivity curve of the speaker ( I was sloppy in writing it is the inverse of the DI, but it is related to that). Now with the Harman headphone curve, I get that it corresponds to the Harman room curve which in turn corresponds to flat anechoic for a well engineered speaker of orthodox directivity. It is that last piece I am curious about. Why does the headphone wearer care about typical speaker directivity? Maybe, as you say, it is 'natural to our evolved sense of what stuff sounds like in a room.' Does this imply that a listener who is used to less orthodox, well engineered, flat anechoic speakers (like omnis, dipoles or whatever) will have evolved a different sense of what is natural? Would they prefer a different headphone curve? Maybe that is right even if I find the disconnect to some absolute measure of flat or accurate a bit disconcerting. I just wonder if there are any other theories that could explain why that specific curve should sound natural. Fair enough, Sean is the leading empiricist in the field, he does not have to speculate! The whole body vibration impact on bass perception is interesting and a somehow more satisfying explanation of one piece of the puzzle than just familiarity.

 

[Robbo99999]

No, I have not tried it..but I understand the rationale behind it.

Let's be honest. Listening to stereo music through headphones has nothing to do with reality in a spatial sense. It is a spatially-compromised experience. Yet, many people get pleasure from it, and that is fine.

Personally, I am amused when audiophiles start talking about the better imaging of this headphone versus this headphone. For me, it's mostly inside my head or slightly outside, and rarely if ever out in front of me.. Maybe I'm drinking the wrong proof of scotch or smoking the wrong stuff ?


In the realm of spatial experiences, all headphone listening sucks compared to a 7.4 or 22.2 loudspeaker experience. I wonder if these people have ever had such an experience??


Binaural recordings with head-tracking (and personalized HRFTS) at least gets images outside your head, and done well you can localize in 3D space and get externalized auditory images in front of you. That is the future of headphone listening IMO. This is what we are working on now. It's a project where we are measuring individualized HRTF's different ways, using machine learning to predict HRTFs from sparse data sets, and applying them to binaural playback over headphones and loudspeakers ---so you don't get a spatially compromised experience.

I'm one of those weird "audiophiles" where headphone listening can sound very similar to speakers in terms of spatiality, but only with my K702 headphones! (I'm talking music listening in my previous sentence). In terms of localising sounds in 3D space I can absolutely do that using my K702 headphones EQ'd to the Harman Target & combined with Soundblaster 7.1 Virtual Surround sound processing - I'm talking about gaming here.....using this system I can recognise sounds in front & behind & left & right on the spectrum of an arc surrounding me and spin directly to that sound. So I don't know if lots of this gaming practice has also given me the "ability" to spatialise 2 channel music on headphones, but like I said it's only really with my K702 that it sounds like my speakers in terms of spatial qualities.

(Ha, I also don't take drugs, and only drink sometimes!)

 

[raistlin65]

If I tried to publish a paper on preferred headphone/loudspeaker targets and didn't know the playback levels at which the adjustments were made, the paper would be rejected for scientific reasons.

There has been some research on the topic of preferred listening levels. For dialog on television dialog it's 58 dBA and home theater ~ 64 dBA. The preferred level depends on background noise and people tend to turn it up with increased background noise. Dolby et al need to know this for setting dialog normalization

http://www.aes.org/e-lib/browse.cfm?elib=15150

And now people are studying preferred levels in headphones because they are trying to limit the exposure to noise to limit hearing loss.

Maybe you might want to partner with Harman/Samsung marketing? See this as marketing/UE research that finds out what happens with products once they get in the hands of consumers? If you could collect 1000 or more responses to the test, wouldn't that be useful to them?

Seems very possible to collect a lot of responses. It would allow people to see what EQ works best for them, and you could provide the parametric EQ presets, instead of relying on third parties to provide them. And if the site shows a running total on the results, some people would do it simply to see how they compare to others.

Whichever EQ profile ends up being most popular could also be built into K371BT as an optional DSP that could be enabled. So there seems value here.

Then if the results end up different from what you would predict, that's good reason to design a clinical study to investigate further.

And thanks for the link. Unfortunately, AES individual article access is a little pricey for those of us who are simply hobbyists. Too bad it's not open access, but it is what it is (no sense getting into that debate).

However, I was wondering what the Harman Target Response reference volume is that was used for calibration in your studies? Seems useful for people to know who are using HTR with their headphones.

 

[Robbo99999]

Precisely what I would expect.
I suppose difference between L and R in a test may give an indication of the magnitude of production variation, but even that would be luck.
To know one would need to test multiple units from multiple production batches - so basically never going to happen.
I would only choose anything, speaker or headphone, which needed minimal or zero EQ personally and have generally bought the actual item I auditioned, not a shop model of the same "model".
Very hard to do nowadays, so hifi is real "pot-luck"

I don't think the variation between headphones of the same model is significant enough / often enough to be concerned that headphone EQ's based on measurements from people like Oratory are invalid......as in I've had great experiences with massive sound quality improvements by using Oratory's measurements for my own EQ's as well as using his EQ's.....so when Sean was commenting on this topic by saying "all bets are off in regards to what you are listening to" with regards to quality control on sub $300 headphones I find this to be an overdramatic statement on the situation. It doesn't mean you can't get a better experience by using for instance Oratory's measurements, instead it means you might be really quite unlucky and end up with a sample that is significantly different, but I bet you'd have to be pretty darn unlucky for it to be significantly different.....and even if there is some difference then it doesn't mean that Oratory's EQ wouldn't improve it....it probably would because I guess the deviations would be in certain places in the frequency range rather than grossly incorrect accross the whole board. I think he was being overdramatic in his statement and I think some people are taking it out of context.

 

[bluefuzz]

Does this imply that a listener who is used to less orthodox, well engineered, flat anechoic speakers (like omnis, dipoles or whatever) will have evolved a different sense of what is natural?

No. Because evolution takes place over millenia, not over a lifetime. Our sense of what 'sounds right' is much deeper engrained.

 

[Sean Olive]

I agree with you it would provide some meaningful insights. Another way would be to collect people's insights from existing customers using the headphone app.

Sorry about the paywall. The article is not worth purchasing -- but I just added it as a reference.

Without lo

I don't think the variation between headphones of the same model is significant enough / often enough to be concerned that headphone EQ's based on measurements from people like Oratory are invalid......as in I've had great experiences with massive sound quality improvements by using Oratory's measurements for my own EQ's as well as using his EQ's.....so when Sean was commenting on this topic by saying "all bets are off in regards to what you are listening to" with regards to quality control on sub $300 headphones I find this to be an overdramatic statement on the situation. It doesn't mean you can't get a better experience by using for instance Oratory's measurements, instead it means you might be really quite unlucky and end up with a sample that is significantly different, but I bet you'd have to be pretty darn unlucky for it to be significantly different.....and even if there is some difference then it doesn't mean that Oratory's EQ wouldn't improve it....it probably would because I guess the deviations would be in certain places in the frequency range rather than grossly incorrect accross the whole board. I think he was being overdramatic in his statement and I think some people are taking it out of context.

Maybe I will show you some data on variance in headphone samples to explain what I mean. I have 10-30 samples of the most popular headphones so I'm not speaking based on speculation/

It didn't mean to imply Oratory's EQs are not useful. I'm just making the statement you cannot be 100 % certain that it will get you to the Harman Target unless you measure your own sample. Things like medium/high Q resonances can shift in manufacturing and those are particularly vulnerable to EQ errors. And there are measurement and positional errors that are particularly prone to EQ errors at higher frequencies.

Of course you can take measures to minimize those errors by smoothing the measurements, taking averages through multiple reseats which will minimize the Q/gain of the filter applies.


When we did our large listening studies using multiple samples of the same model, we have to carefully pick and sort them and in some cases equalize them to ensure we were delivering the same signals to all the listeners' ears. It's not a trivial matter.

 

[Frank Dernie]

I find this to be an overdramatic statement on the situation.

Are you a production engineer experienced in the problems of sample variability in mass produced inexpensive items? Particularly consistent high frequencies?
If not I am afraid your opinion is of minimal value compared to @Sean Olive or even me.
Sorry.

 

[Robbo99999]

I agree with you it would provide some meaningful insights. Another way would be to collect people's insights from existing customers using the headphone app.

Sorry about the paywall. The article is not worth purchasing -- but I just added it as a reference.

Without lo


Maybe I will show you some data on variance in headphone samples to explain what I mean. I have 10-30 samples of the most popular headphones so I'm not speaking based on speculation/

It didn't mean to imply Oratory's EQs are not useful. I'm just making the statement you cannot be 100 % certain that it will get you to the Harman Target. Things like medium/high Q resonances can shift in manufacturing and those are particularly vulnerable to EQ errors. And there are measurement and positional errors that are particularly prone to EQ errors at higher frequencies.


When we did our large listening studies using multiple samples of the same model, we have to carefully pick and sort them and in some cases equalize them to ensure we were delivering the same signals to all the listeners' ears. It's not a trivial matter.

I see what you mean, yes, that makes sense and I definitely don't find that outrageous. Yeah, that would be really interesting to see intersample variation you've measured for a model of headphone(s). That would certainly put it into perspective, and it might show some patterns of where they might vary in the frequency range most often (perhaps).

 

[Robbo99999]

Are you a production engineer experienced in the problems of sample variability in mass produced inexpensive items? Particularly consistent high frequencies?
If not I am afraid your opinion is of minimal value compared to @Sean Olive or even me.
Sorry.

I was mainly saying that I thought you were taking his quote out of context.

 

[pozz]

@Sean Olive Could you please comment on this statement by Dan Clark (of Dan Clark Audio/MrSpeakers)?

https://www.soundstagesolo.com/inde...g-headphones-part-1-paul-barton-and-dan-clark

Dan Clark: We try to have a general curve, but one of the interesting things about curves is that there are headphones that don’t sound like they measure. I think it’s because headphones with fundamentally different designs will interact differently with the acoustical impedance of the coupler used to measure them. We’ve tested some headphones as part of our research and development that might measure dead flat up to 4kHz, but they sound like they have a lot more bass than others that have more boosted bass when measured. So you really can’t rely on things like the Harman curve to tell what things sound like.

Note that Dan Clark goes on to say that, "I always listen before I measure because I don’t want to bias myself with measurements." So it's clear that he relies on sighted listening.

The main thing I'm interested in is his statement about coupling and the resulting frequency response. I don't understand why a headphone measuring flat well into the concha gain region would be perceived as having stronger bass.

 

[Frank Dernie]

I was mainly saying that I thought you were taking his quote out of context.

I don't think I was.
Production variability in inexpensive transducers is considerable and the idea that using an EQ that was calculated from measurements of one pair of headphones on a different pair of the same make and model is naive, at best.

 

[Robbo99999]

I don't think I was.
Production variability in inexpensive transducers is considerable and the idea that using an EQ that was calculated from measurements of one pair of headphones on a different pair of the same make and model is naive, at best.

I think you've misread the situation, even Sean said just now that for example Oratory's measurements are useful, just that you can't be 100% certain that you'll be bang on the Harman Curve with your own particular set of headphones.....I can live with that kind of variation/philosophy. Doesn't mean you shouldn't use measurements to EQ your speakers or headphones. (Even it is only based on one pair then it could still vary in it's usefulness between better than nothing to not significantly different at all ("perfect")....depending on how much variance there is between units for that particular model of headphone).

 

[bobbooo]

Isn't it the present, not just future?

Apple's Airpods Pro and Max have already hit mass market in a huge way, although the numbers using the Spatial Audio feature probably aren't huge yet.

Try the past The AKG N90Q active headphones were released way back in 2015, introducing Harman's TruNote technology - auto-calibrated, personalised frequency response via tone sweeps played and reflections measured to characterise and adjust for the acoustics of your ear (see Ulrich Horbach's AES paper). Now this personalised frequency response isn't based on a full HRTF, but it is based on the PRTF (pinna-related transfer function). On top of that the headphone also has '2.1 Studio' and '5.1 Surround Sound' spatial modes that are based on HRTF models (albeit not personalised):

Three different spatial listening modes are provided. Each mode is characterized by a different spatial perception of the apparent acoustic surroundings. The first mode Standard renders the music unprocessed, like in any conventional headphone. This is useful in particular, if you use external processors such as Dolby headphone or DTS headphone X. The second mode Studio brings the sound stage to the front of the head, without adding any room effect, by means of a novel crosstalk circuit derived from a patented, simplified model of head-related transfer functions. The third mode Surround adds simulated reflections around the head, designed so that you perceive the sound stage at a greater distance, without disturbing artifacts such as coloration or reverb.

 

[Music1969]

Try the past The AKG N90Q active headphones were released way back in 2015, introducing Harman's TruNote technology - auto-calibrated, personalised frequency response via tone sweeps played and reflections measured to characterise and adjust for the acoustics of your ear (see Ulrich Horbach's AES paper). Now this personalised frequency response isn't based on a full HRTF, but it is based on the PRTF (pinna-related transfer function). On top of that the headphone also has '2.1 Studio' and '5.1 Surround Sound' spatial modes that are based on HRTF models (albeit not personalised):

Another example of Apple not being the first but they're gonna make everyone bring this kind of stuff back and advance it forward at faster rate.

Already now with their Airpods Pro and Max (Spatial Audio feature) but also when they kick off their VR headsets at some point.

 

[Sean Olive]

Try the past The AKG N90Q active headphones were released way back in 2015, introducing Harman's TruNote technology - auto-calibrated, personalised frequency response via tone sweeps played and reflections measured to characterise and adjust for the acoustics of your ear (see Ulrich Horbach's AES paper). Now this personalised frequency response isn't based on a full HRTF, but it is based on the PRTF (pinna-related transfer function). On top of that the headphone also has '2.1 Studio' and '5.1 Surround Sound' spatial modes that are based on HRTF models (albeit not personalised):

Yes, I am aware of that headphone and the technology. I didn't consider that because it designed more for stereo content-not immersive audio content like ATMOS, MPEG-H etc., which didn't really exist when it was developed.

Have you ever measured the headphone before and after TRU-NOTE or compare them? Curious what your thoughts are.

 

[Sean Olive]

@Sean Olive Could you please comment on this statement by Dan Clark (of Dan Clark Audio/MrSpeakers)?

Note that Dan Clark goes on to say that, "I always listen before I measure because I don’t want to bias myself with measurements." So it's clear that he relies on sighted listening.

The main thing I'm interested in is his statement about coupling and the resulting frequency response. I don't understand why a headphone measuring flat well into the concha gain region would be perceived as having stronger bass.

That's interesting because his latest headphone is advertised as closely matching the Harman Target curve and the attached measurement confirms it. So here is an example where the acoustic impedance of his ear and coupler seem to be working in harmony with the headphone.

There has been a bit of work published in this area including the paper by Hammershoi and Moller.
see https://vbn.aau.dk/ws/portalfiles/portal/227875204/1995_M_ller_et_al_AES_Journal_b.pdf

Basically the acoustic impedance of the headphone interacts with the acoustic impedance of the ear and you can observe changes in the response when the ear canal becomes more blocked. Worst case is In-ear headphones which completely occlude the ear. The least effect is with open back or headphones like K1000 that sit inches away from the ear. Closed headphones are somewhere in between.

 

[Sean Olive]

Another example of Apple not being the first but they're gonna make everyone bring this kind of stuff back and advance it forward at faster rate.

Already now with their Airpods Pro and Max (Spatial Audio feature) but also when they kick off their VR headsets at some point.

I went to the office today and heard the Max for the first time. I only heard pink noise bursts through it because I was doing a localization test but it was quite impressive. The ANC was very impressive: I could not hear the experimenter giving instructions without taking it off. THe experimenter said he cannot wear it more than 40 minutes without pain so comfort may be an issue. Too bad because it would be a good headphone for long flights

 

[DDF]

That's interesting because his latest headphone is advertised as closely matching the Harman Target curve and the attached measurement confirms it. So here is an example where the acoustic impedance of his ear and coupler seem to be working in harmony with the headphone.

There has been a bit of work published in this area including the paper by Hammershoi and Moller.
see https://vbn.aau.dk/ws/portalfiles/portal/227875204/1995_M_ller_et_al_AES_Journal_b.pdf

Basically the acoustic impedance of the headphone interacts with the acoustic impedance of the ear and you can observe changes in the response when the ear canal becomes more blocked. Worst case is In-ear headphones which completely occlude the ear. The least effect is with open back or headphones like K1000 that sit inches away from the ear. Closed headphones are somewhere in between.

This was something we needed to manage all the time in telecom when designing and testing high acoustic output impedance handsets or headsets. The solution to try and schieve consistency was to use a rigid coupler (instead of HATS or KEMAR) and then use a calibrated leaky coupler in between. Can't recall who sold it, long time ago.

 

[bluefuzz]

Oratory's measurements are useful, just that you can't be 100% certain that you'll be bang on the Harman Curve with your own particular set of headphones.

For the half-dozen pairs of headphones I own, I can definitely say that doing my own measurements on a MiniDSP EARS, has resulted in vastly better EQs than using generic measurements/EQs from Oratory/Crinacle et al.