This is a nice summary of the stages people go through when diving into measurments and why frequency response ends up being the main thing used

https://youtu.be/LrIoNMeo_GI

It is 100% the most important metric for sound quality in headphones. There is no denying that. A lot is contained in FR, and simplifying it to "loudness at different frequencies" is not quite right.

What exactly is different from the 10$ earbuds compared to nicer headphones?

There are some that say that frequency response is everything and all that matters. Saying that frequency response alone is responsible for literally everything including imaging, soundstage, detail retrieval, bass slam, you name it.

Also, not everyone wants to use EQ.

When we talk about "audio quality in general," much of that can actually be gleaned from a savvy interpretation of the frequency response graph. If it sounds "muddy," that's likely because there's too much bass and the drop in volume between the ~80 Hz and ~200 Hz domains is too abrupt. If it sounds "piercing," that likely means it's too loud between the 4 kHz and 10 kHz. If it sounds "unnatural," then there's probably some weird spikes between 500 Hz and 4 kHz.

Interpreting frequency response graphs can be a very nuanced thing, and even (perhaps especially) the most experienced reviewers often swear that they don't tell the whole story. If you look up graphs of the KZ CRN, you'll find that it looks extremely accurate—but many reviewers felt that it had unnatural lower treble. The Campfire Andromeda, meanwhile, has a rather weird-looking graph, but almost every reviewer I've read says its tonality is gorgeous, if a bit odd.

Others will probably chime in and point out that there are other graphs you can use to understand a heaedphone. The most notable one is the waterfall graph, which (allegedly) documents resonances where the headphone takes an unnaturally long time to stop sounding when a specific frequency is played. Others argue that this just isn't how headphones work. I don't know enough about physics to say who is correct.

But I would consider the video u/SupOrSalad linked to be authoritative on the subject.

You're going to get downvoted a lot for this observation, but you are right. Frequency response is separate from soundstage, imaging, detail, and dynamics, though the general consensus on reddit is that fr is responsible for all aspects of a headphone's sound.

Reviewers provide frequency response in their reviews because it's one of the only objective factors in sound quality they can provide. EQ can be very helpful in fixing a headphone's flaws, but many people don't want to deal with that, and I suspect that's why many reviewers emphasize frequency response. It's much easier to just buy a headphone that's well tuned from the start.

>simplifying it to "loudness at different frequencies" is not quite right.

Is there something else it's showing that I'm not aware of? X-axis shows frequencies and Y-axis shows decibels. "Loudness at different frequencies" seems like exactly what the graph is showing.

FR is 99% of the sound. You can modify it with EQ but only up to a certain threshold

Frequency response is basically the only measurements that I can... hear. THD, CSD, impulse response, etc., doesn't always correlate to what I hear out of headphones. Not to say that's not useful, but seems less reliable in terms of predicting what something sounds like.

for the most part, yes, but there are other things that come into play. elevated treble can sometimes create a sense of detail, certain peaks can mask surrounding frequencies, etc. Truth is, there are a lot of things that seem not related to loudness at different frequencies but actually are.

That's essentially what I was getting to in the second part of my post. It's the only objective measurement a reviewer can provide that has a useful basis for comparison for the average person.

thanks

I get that but I do use EQ, so when looking at reviews I'm more interested in the stuff I can't change about a headphone, not the stuff I can.

I wouldn’t buy a headphone I wouldn’t listen to without PEQ, because I don’t always have PEQ.

FR is only so useful, the blathering of reviewers usually even less so. In the absence of being able to test a headphone yourself, both have their uses.

I would say with the 10$ buds the instruments are harder to separate, you can't quite "pick out an instrument to listen to". Idk if that makes sense. The detail in the sound might be lost and it just generally sounds "bad"

Kinda like how a low quality file can make music sound bad, except in that case I understand why and how and in this case I don't. If I had to guess it's how accurately the driver reproduces the actual signal it's given. But again I don't know, that's why I'm asking.

That might be true but I'm more interested in the aspects of a headphone I cannot change, since those are ultimately what will decide if I like it or not.

And for an audiophile audience who spend thousands on audio equipment I really don't think fiddling with a few sliders to make their stuff sound better should be too much.

Thanks for your explanations :D

That’s critical thinking done correctly. I like it. I’m going to steal it.

I kinda get you but those things don't really only depend on fr.

you can have two headphones with equally elevated bass where one is muddy and the other is not. same with treble.

or am I dumb?

I'm the same as u

But they are related to loudness at different frequencies, though. Even how we perceive transient response is related to loudness at certain frequencies, which is why things like impulse response aren't so useful.

Muddiness usually comes from specific bass frequencies, typically the upper bass. So it's pretty easy to see on a graph which headphone is likely to be muddy. Same thing with treble, the specific spikes tell you which headphone is more likely to be unpleasant.

This is an important point. Some headphones just don't handle EQ well, so you can't just EQ to fix things.

i think we are agreeing, but theres a slight misunderstanding. I interpreted his saying of "loudness at different frequencies" as how he used graphs. I thought he meant basic stuff like "oh, theres more bass", which is true but limited in use. i agree with your statements tho, it technically is loudness at different frequencies, but interpreting graphs can go (a little) beyond that

it is hard to know what causes them to sound different because they are two extremely different products.

But even then, what metrics could cause them to sound different? Ignoring variables that affect perception (price, physical sensation, build quality, hearing, etc), we find that the most important objective metric is FR.

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Since headphones are minimum phase devices, all those other things, including separation, speed, imaging, and soundstage, do depend on the frequency response.

However it's simply that's we don't know how to fully interpret these information from a FR graph yet, and the FR measured does not equal the FR you will actually hear (due to HRTF from pinna gain for overears and resonance peak from ear canal for IEMs, since every person's ear anatomy is unique)

ok so what does that actually mean? :D

yeah ok but why? you haven't addressed any of the points I mentioned.

from the fr graph you can guess at things like muddyness or clarity or whatever but ultimately they are guesses. from what I heard there are headphones with wild looking graphs that sound great and headphones with smooth level graphs that suck.

so sure, fr is important, but why?

Measured frequency response (at least for over ears) will not match exactly what you hear because the measurement rig has a different anatomy than your ears.

This is a graph of 40 different peoples perception of FR, and the divergence starts at 1Khz.

So how a headphone looks on its FR, and how it is perceived by the individual, is totally subjective.

Check out the paper: https://vbn.aau.dk/ws/portalfiles/portal/227875122/1995_M_ller_et_al_AES_Journal_a.pdf

There's way more non measurement reviews of audio equipment out there than with measurements. Maybe IEM reviews are the exception.

edit: I know this sub doesn't like audiosciencereview but this video on frequency response and psychoacoustics is good, if a bit dense

It is important because it is the (one of) the only objective metric with which one can evaluate headphones.

If you look at forums, reviews, videos, etc, you quickly realize how everyone likes different things. Worse is that people often hear the same gear differently as well. For example, you might like that "wild looking graph" headphone, but someone else might dislike it.

Soundstage, detail, imaging, dynamics, transients; what do they actually mean? Again, no solid definition, and again, people perceive these differently.

It all comes down to having at least one thing that is objective and (mostly) consistent across every reviewer. And most reviewers dont base their opinions just on the graphs, i have not seen one reputable reviewer do as such. They still rely on their hearing for those mysterious technicalities.

>Soundstage, detail, imaging, dynamics, transients; what do they actually mean? Again, no solid definition, and again, people perceive these differently.

yes but those are the things that I cannot tune myself, so those are the things I am most interested in.

If I buy new headphones and it has too much bass for my liking, I can lower the bass with EQ, problem solved. If I buy new headphones with bad imaging or soundstage then tough luck, I'm stuck with that.

and frequency response is just as subjective as any other metric. I know reviewers don't base their opinions entirely on the graph, but it's what they show and what they explain "sound quality" with.

That is perfectly valid, a lot of people buy technically capable headphones and EQ its mediocre tonality to something they like. But like others said, that isnt always possible.

Frequency response is also NOT subjective. Perception of FR is, but the measurement itself is objective. Whether people listen to the reviewer's subjective interpretation of the graph is up to them.

So now I know that:

1. frequency response doesn't actually tell you anything.
2. oh wait, actually frequency response tells you literally everything you could possibly want to know.
3. but yeah no actually it doesn't really tell you anything lol

cool...

Yeah, I think its actually one of the least explanatory videos the headphone show ever made. I wouldn’t show it to anyone who is new to the Hobby honestly. To make it short: graphs give you a pretty good idea about a headphones tonality. And if you know what you like and how the headphones you like measure you can often tell how another headphone sounds in comparison through the graphs. But since your ears work different than a measuring rig you will always need to listen to the headphone to actually know if it sounds good to you.

Frequency response graphs show the most important single metric of a piece of audio equipment—the linear distortion. Linear distortion is far more easily audible and objectionable than nonlinear distortions. I don’t think anyone claims that FR is ‘everything’ but it is definitely the most important thing.

Sorry for just dropping the video earlier and dipping, I was at work but really wanted to chip in on this topic.

Ok so first, it's good to have an idea how we hear and what the driver is doing in regard to pressure waves when generating sound. https://imgur.com/a/AYU9ciU So in this image it depicts individual frequency waves and then they are combined in an analog signal for the driver to create them, they are all added (and subtracted) together into a single waveform that the driver follows. That creates the pressure waves that our ears pick up and extract information from. Now when applying that to frequency response, the varying SPL of differing frequencies has a direct affect on the shape of the waveform due to differing amplitude in various frequencies.

With that in mind it's also good to know about things like auditory masking. When multiple close together frequencies are played, if one is substantially louder than other similar frequencies being played, our brain filters the quieter ones out. The range of frequencies masked is dependent on how loud the peak is. So with headphones that have substantial variation in it's FR, it may sound either more "detailed" or less "detailed" than another based on it's FR. Personally I believe this is also one of the factors that causes the perception of "fast or slow" headphones, despite their drivers not actually responding in a "fast or slow manner" (in the sense its often described).

That said, it's not discounting headphones, different drivers, and the research or quality put into them. Different headphones and drivers may have their own unique frequency response due to various factors, and EQing is more like bending that overall tonality, but specifical characteristics of the FR that may make them sound unique will still be present.

So no you can't just look at a graph and know exactly how it will sound, or use a FR graph to EQ it perfectly to you because of differences in transfer function and acoustic impedance. Even if they measure the same on a graph, it may differ at your eardrum.

To summarize, FR at your eardrum in theory contains all the information you need, but actually extracting that information from FR is not reliable and FR made on standardized rigs is better used as a tool, but still trust your ears first

Subjective sound impressions + quick look at FR is a good combo. I like the way DMS does it but I don't trust him too much.

If you look at RTings, in addition to frequency response there are other objective measurements that can describe headphone performance, and you can maybe learn your own ears and head and how they'd transfer those numbers into the phenomenology of listening...maybe.

It's not perfect, but your other choice is watching Christopher Suede videos and trying to assign meaning to words like thick... ephemeral...euphonic...dark...bright...warm...analytic...fast...tight...velvety

Not even just ear anatomy - room acoustics, humidity/air pressure, ambient noise, dust and pollen levels, the amount of hair on their head, head size, skin temperature, the exact angles of the headphone mounted on their head, etc.

And that's on top of the fact that literally no two headphones - even of the same make and model - are exactly the same.

Trying to EQ low quality headphones, say some cheap ones from ebay, is like trying to make your pebble shine by polishing it. In my opinion, for the most part, frequency response is basically almost everything. Except for soundstage and imaging. Frequency response does have a play in soundstage and imaging, but there are other factors, like with over ears, the space between the driver and your ears, your pinna, the shape of your ear canal.

>oh wait, actually frequency response tells you literally everything you could possibly want to know.

For iems, frequency response tells you almost everything.

Just to add in, literally everyone on this sub screams minimum phase this, minimum phase that….in theory… sure! In reality, a very small number of headphones actually behave this way, most of the favorite headphones in this sub and totl cans do NOT behave as minimum phase systems for their FULL bandwidth.

That is all . That’s the only point I wanted to make. Headphones aren’t often TRUELY minimum phase. The end. Let the downvotes begin.

• a headphone designer who has measured many many headphones.

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>So how a headphone looks on its FR, and how it is perceived by the individual, is totally subjective.

I find this highly debatable. First of all as the study points out the individual hrtf is basicly the same as the mean up until 2khz for open ear canal and 5khz for blocked ear canal. This means that at least the bass and mid frequencies are perceived the same. Which you can also see on your picture where the lines basicly deviate 1db up or down at worst, thus we can say based on the just noticable difference for sound (1db) the stimulus is pereceived the same. Above 2khz and 5khz the difference get's larger but still when you look at the right graph which shows the individual hrtf variations for +-1 std are still very low (+-1.5db variation for ~70% of the people) under 7/8khz. Above that deviation get's quite big but that is also the area where tweeters stop to play, music has less content and hearing loss starts to become very frequent. Thus the importance of that is debatable imo.

It really depends on how noticable amplitude change is perceived to be but based on the known theory and my own experience I would say that for at least the majority of the people most headphone will sound the same, differences probably will be in perceived treble levels which other research also proofs (treble sensitivity etc.).

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The frequency response just shows the idea of what it would theoretically sound like. Frequency response doesn’t show you how it sounds. You have to test the equipment to hear it.

FR is a lot, the $10 earbuds would have atrocious FR. Either non existent or bloated AF bass with ridiculous peaky treble that you can't do anything to fix. Soundstage and some other things aren't modifiable at all really typically has to do with things like physical driver orientation in the housing etc.

I'm a huge fan of EQ. At this point it's readily available in things like the Qudelix5K for a very reasonable price allowing you to PEQ all the things. Why wouldn't one opt for making their headphones sound better given the chance. With auto EQ there's even a reasonably easy means of going to a neutral signature and making modifications from there.

That being said not every driver is created equal. Just because you've made modifications in an EQ does not mean the driver will be up to the task. Lower end cheap drivers will be too shitty to EQ and "fix" it'll just bleet and distort. Also just because a headphone is expensive does not necessarily mean it will EQ well.

Some headphones like Planar IEM's are well known for their ability to respond to EQ.

It would be nice if you could provide some examples and elaborate on what you mean.

I know this is an anecdotal example so feel free to dismiss my following subjective impression.

The Meze 109 Pro is lauded and praised by many reviewers and people in the headphone community. I found its treble to be way too hot and I couldn't comfortably listen to more than 1.5 songs with it. This anecdote ties into the sentence you conclude with

> most headphone will sound the same, differences probably will be in perceived treble levels which other research also proves (treble sensitivity etc.).

My experience with the 109 differs from most. And it sounds different to me than it does to someone else.

If you think that any given headphone will sound the same to everyone who tries it, then we disagree and I'm not budging on this point. I don't mean to come across as stubborn or anything but there is not a single headphone that everyone agrees to sound the same. Sure there are general trends e.g. DT990 is bright, but how much a headphone is enjoyed will vary from person to person.

Most headphones behave as a minimum phase system… for some of their response range, but many popular headphones (audeze, hifiman, sennheiser etc) have large portions of nonlinear and non- minimum phase response within their operating range. It just bugs me that everyone screams minimum phase and few of them actually understand what it means and /or if it’s even true.

For IEMs, changing the insertion depth changes not only the resonance peak but also the treble frequencies by 3-5db. That's why the Z1R treble is so divisive. I believe crinacle or some other reviewers have the measurements for that.

For over ears, anecdotally my left and right ear HRTF is different enough I can hear the difference between them when doing frequency sweeps.

Well according to u/oratory1990, whose an acoustic engineer with a phd, it headphones are minimum phase

>My experience with the 109 differs from most. And it sounds different to me than it does to someone else.

Let me first start of saying that what you're hearing is not wrong, I 100% believe you. This is important because the reason you hear what you hear could have in my opinion based on what I know about this topics and what I read could have 2 reasons. The first is your hrtf doesn't match with the mean as pointed out in the paper we're talking about; you literally hear different.

The other reason is probably that you are used to other headphones which have a different response and because the meze probably has more highs than the other headphone you perceive it as too much highs. This means that the error is not that you hear different meaning (e.g. you have a different hrtf which was the point I was making) but that you are used to other headphones or just have a different preference. Comparing the Meze to the headphones in your flair seem to confirm that it indeed has more treble meaning the target represents your hrtf probably pretty well.

Really my point is that we are (most of the time, 80%+ of the people) not hearing differently but that we have different preferences (or known/used to targets), this is also supported in the harman target research paper which pointed out that some people like more bass and some less highs. This means in short (in my scientific based opinion at least) that if we both listen to a pair of dt990's after having listened to hd650's for a good while (so it is our definition of neutral and our only audible memory of a reference) that we both would think the dt990 is a bright sounding headphone and not still have different ratings because our ears are literally different.

Interesting fellow oratory, no disrespecting the legend, but I also have a graduate degree in acoustics, and headphones are my full time work. I’ve measured many many headphones and in fact found, as I noted, that many headphones aren’t minimum phase “for their entire bandwidth” and I highly doubt he’ll disagree with that statement. It’s common knowledge in the headphone industry. There’s even some good plots of it floating around this sub , if I recall specifically calling out the LCD2, focal (forget which one), m50s, and hd600s. If you don’t believe me dig around and you’ll find them. - not that that in any way makes them bad headphones, again, I just get frustrated when people just echo other comments they read when they don’t know what it means/it isn’t completely true

Fair enough, thank you for sharing

> for some of their response range, but many popular headphones (audeze, hifiman, sennheiser etc) have large portions of nonlinear and non- minimum phase response within their operating range.

Can you elaborate further? What makes it non-linear or non-minimum phase?

Here is the link to this subreddits wiki page supporting this statement/comment, that headphones are indeed not always minimum phase over the entire bandwith.

To simplify it a bit, I’ll explain an example vs the actual concept as it gets kinda messy. A consequence of being minimum phase is that: Amplitude and decay time are proportionate. / louder sounds take longer to decay than quieter sounds, and the relationship between these two is constant. Areas where a system is NOT minimum phase would have that relationship breakdown such that either the proportion changes (got quieter /louder and the decay doesn’t scale linearly or equally to other frequency bands). This has consequences - though not necessarily negative. It just causes some issues in the common argument that “frequency response is everything, it tells all the info you need because headphones are minimum phase”. And while admitting it tells you a lot, I can’t help but be a little bit of a stickler just because it annoys me when people echo what they read elsewhere in other comments without knowing what it means. But now you know! https://www.reddit.com/r/headphones/wiki/resourcesindex/where-to-find-headphone-measurements/minimumphase-csd-ir/ here is another fairly short read I found from a while ago that discusses it a bit more without getting tooooo deep In the weeds

The reason frequency response graphs are focused on so much is because it's the only real way to know how a headphone/IEM sounds before buying it. There are a lot of aspects that a headphone can have other than tonality, but tonality is arguably the biggest factor of determining how a headphone will sound. Before FR measurements were standard, you had basically no reference as to how the headphone would sound before you bought it, so you could only really go off reputation and recommendations.

I'm also baffled by the "fr only matters" stereotype. Who says this? Anyone can easily disprove this by buying a set of awful headphones and eq'ing them to a graph, only for them to sound arguably more shit. FR doesn't tell the whole story, but it's way better than nothing, and reviewers have gotten a while lot better about nitpicking technical performance, so you can go to them if you want info about a headphone's audio quality

> but that you are used to other headphones or just have a different preference.

100% true. I prefer dark headphones and EQ in treble to taste / mood / genre.

> Really my point is that we are (most of the time, 80%+ of the people) not hearing differently but that we have different preferences (or known/used to targets),

I can get behind an 80/20 weighting of preference to literally hearing different. I'm still holding onto a shard of hearing differently because I don't know how some people can listen to Beyerdynamics (990 and 1990) even after testing headphones with different signatures. They both pierce my soul haha.

It'd be cool to be a participant in that study and get our own HRTF profile.

>I can get behind an 80/20 weighting of preference to literally hearing different. I'm still holding onto a shard of hearing differently because I don't know how some people can listen to Beyerdynamics (990 and 1990) even after testing headphones with different signatures. They both pierce my soul haha.

As I said in my first post it is not entirely clear how that is perceived by all people. But I know from reading Floyd Toole's book and doing some research, because I also find this rather facinating (Why do people love speakers/headphones with ear piercing highs?). That hearing loss could also be a potential reason why some people seemingly enjoy it, besides what is already stated see here for example noise induced hearing loss 'notches' https://www.researchgate.net/figure/Audiograms-showing-onset-and-progression-of-noise-induced-hearing-loss-First-a-notch_fig3_264555852. Which quite coincedently are exactly around the treble peak of a beyer headphone... With normal hearing loss it also kind of acts like a low pass on the sound making the highs less audible; https://www.researchgate.net/figure/Age-related-hearing-loss-according-to-the-International-Organization-for-Standardization_fig1_338597788

Frequency response, as a physical property of a headphone or IEM, dictates what you will hear (barring deliberately added DSP or exceptionally poorly designed edge cases). That doesn't mean that graphed measurements of said frequency response will necessarily tell it to you. The two are different things, which is the source of much confusion.

Yes and no. Most people don't and won't EQ even if it's free sound quality and easy to start with presets. The tuning often explains like 90% of the sound and many cheaper headphones and IEMs can EQ'd to be very competitive with something good 10 x the price. Soundstage and macrodynamics are mostly separate from tuning, but detail, separation etc are usually highly correlated with the tuning.

Do you have an example of a specific headphone with the excess group delay measurements that show a significant deviation from minimum-phase? Just cause you mention that a lot of popular headphones have large portions of non-linear regions. Like I see the M1060 as an example but it's fairly minor. The HD600 and LCD2 graphs (other than noise in the bass region) looks like it's very much minimum phase.

Personally I don't put much stock into measurement graphs other than to get a general feel for the tuning so don't take this is as me being antagonistic. I'm just curious because I haven't really seen an example where there's a clear and significant deviation from minimum-phase.

You can't change any frequency response into any other and you can't change a garbage one into a good one.

Oh not at all, it’s all about learning and sharing. I mean I would say a 5ms delay in the low frequencies in those plots is pretty significant… and then a 2ms deviation in the high frequency as well on the lcd2. I also put a lot more time into listening than graphs myself, but they can be useful. The logical fallacy here is just that if they’re going to say it’s min phase and that, due to this, all information about transients and speed etc blah blah is all wrapped up in the fr. Well that’s just not true, a 4ms group delay in audio is not insignificant and could definitely lead a trained/experienced listener to hear a difference. So while in the grand scheme it doesn’t really matter, sometimes I put my neck on the Reddit echo chamber chopping block and say something 😂

Well but this is just the thing. Some people would absolutely disagree and say that if they have the same bass FR, they won't have different bass response. But others would not! It's one of the most heated disagreements in headphonedom.

Here are my two points:

First, as I said, it's not always so much how much louder the bass is as a whole as how smoothly it transitions into the mids. And this can affect the character of the bass a lot. Second, if you're looking for "fast" bass, that can boil down to treble response too. Bass instruments will have higher harmonics that are affected by higher frequencies, and these can also affect the impression of what sounds clean or not—whether these higher harmonics are rendered accurately.

But I would probably have to try a good planar headphone before I could authoritatively say of myself "no it's just FR but more nuanced" or "there actually is a je ne sais quoi to the bass texturing."

The frequency response graph can give a general description of what the headphone is like. Being linear without any peaks is a sign that it will sound smooth without any parts of the music being over or underemphasized.

Frequency response is the easiest was to demonstrate how headphones will sound for someone who hasn't heard them. They are some of the only objective sound characterization of headphones. They are used to compare 2 headphones and see why they sound different. It's best to look at data about headphones relatively.

You can EQ the frequency response, but it won't sound the best. A headphone without bass adjusted to sound like a headphone which naturally has a lot of bass won't sound the same. (I'm not saying an EQ will make headphones sound bad)

This sub IS AudioScienceReview

What you're describing is technicalities vs frequency response. How "good" a headphone or whatever is; is down to a combination of frequency response and technical performance. But technical ability can't really be measured in as simple a way as frequency response, so it's more subjective. Also, how importantly you weigh one over the other is also subjective and down to your personal experience/taste. EQ is very powerful and I think everyone should use it, but it's also true that FR isn't everything. If it were, you would be able to make two audio devices sound EXACTLY the same with nothing but EQ, but that really isn't possible and that becomes obvious to anyone into the hobby for a while. The remaining portion is loosely described as "technicalities". There are ways to measure aspects of technical performance but like I said before it's a lot more subjective. I think most would agree though that technical performance is almost all down to driver type, material, configuration, surrounding assembly etc. Basically, the moving mechanical portions of the audio device that actually produce sound, and the parts that effect them. It's also worth noting technical performance doesn't necessarily mean the same thing as "detail", since the perception of detail can be greatly affected by both technical performance and FR.

There is way more to this topic so I would suggest you look more into the science and engineering aspects of audio if you want to know more.

For someone just trying to buy headphones though, the FR graph is a good way of understanding how their own preferences are visually represented, and how measured devices line up with those preferences.

I don‘t have a PhD and yes, minimum phase ends usually about an octave below 20 kHz, depending on the size of the front volume.
In-ear headphones normally are up to 20 k and higher since the front volume is so much smaller.

You‘re entirely correct.

Minimum phase system in the general frequencies that a human ear can hear. And the differences between the response time will also be noticed in the frequencies, and the EQ will change that too.

My guess is that differences other than frequency response are related to harmonic distortion, and things like ringing/resonance in the headset cup, mostly.

Harmonic distortion makes it hard to tell instruments apart because pure tones already gain extra overtones which can audibly affect the character of the sound if they are above some -60 dB relative to the main tone, and multiple tones do not blend cleanly, either, but interact and create additional extra frequencies, and it is typically called intermodulation distortion. These extra frequencies could be perceived as extra noise, or timbre changes, or such, and may make it hard to tell instruments apart. It is one of the reasons why I look for harmonic distortion graphs, especially those that have separated 2nd, 3rd, 4th and so forth, as physiological measurements of human auditory system show that the masking of the harmonic distortion mostly covers the 2nd harmonic at some -40 dB level, but barely at all for the higher ones, though there is general tendency for harmonic distortion below -60 dB to be inaudible no matter where it is.

For over-ear headphones, ringing in the cup is probably visible as narrow peaks in frequency response at some specific frequencies, assuming the graph is not overly smoothed. Ringing is usually also visible as minor kinks in impedance graph as well, as the driver behaves somewhat differently at those particular frequencies, and is likely also seen as abrupt changes in the group delay and phase. So I like to see a nice flat group delay plot up to some 10 kHz, to know that there are no phase or ringing issues to be expected. Above some frequency depending on the cup's distance to headset fixture and earlobes, the measurement device itself will add all sorts of phase issues, and generally speaking the measurement above 10 kHz is not usable. For IEMs, I think the measurement reliability extends far higher, though there will be a peak for the ear canal resonance frequency where soundwave bounces between eardrum and the IEM and the exact frequency depends on insertion depth.

By the knowing how one heaphone graph looks like you can understand the character of the sound. You just need to understand what character do you prefer and then it's way easier to find headphones or iems which most likely fit you. But graph won't tell you anything about the technical abilities of headphones. So you can't trust the graph and only the graph.

> And for an audiophile audience who spend thousands on audio equipment I really don't think fiddling with a few sliders to make their stuff sound better should be too much.

As a counter point, if I'm spending thousands on equipment, I shouldn't need to.

>many popular headphones (audeze, hifiman, sennheiser etc) have large portions of nonlinear and non- minimum phase response within their operating range.

Can you please post excess group delay measurements of all these 'many popular headphones' with 'large portions' of non-minimum phase response?

>I mean I would say a 5ms delay in the low frequencies in those plots is pretty significant...

That's measurement noise. See here.

Yes of course the changes would show up in FR but if they’re disproportional and non linear depending on frequency then you in fact cannot extrapolate all extra information from FR alone, you’d need additional information to find the unknown variables. Without a valid min phase assumption there’s too many unknowns to solve. 20-50hz is for sure in most people’s audible spectrum, as is alot of the hf content susceptible to it. Again, not saying this is inherently a bad thing, but it is true. Please see my other comments below for more discussion

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Do you have any evidence excess group delay at these levels is audible?

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So you have zero evidence to present to back up your claims, got it. That's not how science works.

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No need. People who do actual science, interested in the furthering of knowledge for everyone via transparent academic research, rather than secretive industry insiders preoccupied with lining their pockets and an aversion to sharing data except to a select elitist few with NDAs, have already made their research publicly available. So that's a positive group delay audibility threshold of ~1.5 ms for actual music signals, which few headphones will exceed.

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You both seem like reasonable people that just caught each other on a bad day. I took the liberty and nuked the tail of the exchange to stop the escalation.

Happy to re-instate the exchange if both parties think it's worthwhile.