"Bias" of some members towards headphone measurements?

[Jaxx1138]

HRTFs are a result of human anatomy and therefore individual to a person, but measurable and therefore objective. Am I missing something, here?

This statement is incorrect. they are purely subjective.

As explained, the interaction between the headphone as a whole (including pads and housing) and the pinna and ear canal change the sound that arrives at your ear drum. I never said distance has any influence on the transducer. A quick google search turns up papers on pinna interactions like this one, to give just one random example. And a distance of maybe 10 mm is pretty different from 1000-3000 mm. I mean, that's three orders of magnitude - if that isn't significant, what is?

We do not tune a loudspeaker to how an individual hears. Why would you think we would do it for a headphone.? Would you believe an orchestra should be tuned to how anyone individual hears?

I'm not claiming that it did, therefore I don't see why I would provide evidence for this. I simply explained why I recognize that heaving a realistic "standard head" seems like a good comparison tool to me.

But the question is, what is the scientific reason behind this thinking?

Our current measurements are pretty objective, but you can certainly argue that a specific HATS or pinna model isn't the right one or that there's not enough evidence to back up one geometry or another. In the end, the choice of one specific HATS geometry is subjective. Fair enough. I do think, however, that designing a headphone without ever measuring it on real or simulated heads is a bad idea.

This is the current problem with that line of reasoning; It is in fact not a subjective thing but an objective one. We are supposed to be evaluating OBJECTIVE acoustic metrics. My point is we need objective metrics whereas you are arguing it's good enough even though it is clearly wrong. I am not saying NOT TO MEASURE IT. I AM SAYING WE NEED TO MEASURE IT CORRECTLY.

 

[kemmler3D]

they are purely subjective.

Not in the normal sense of the word... everyone has their own HRTF but they can be measured, stored, used for processing, etc. I mean, it's "Head Related Transfer Function", not "How Research-subject Truly Feels".

 

[Jaxx1138]

Right, but speakers don't bypass any of the head/body/pinnae and headphones / IEMs do, so we can say that the Harman curve (or a similar tuning) achieves 90-95%, but the remainder needs to be personalized to work.

To put it another way, the sound that reaches your eardrum and the sound that reaches my eardrum from a given pair of IEMs is probably nearly the same. But, taking a neutral speaker as the reference for neutrality... the sound should actually be different for each of us. Because our HRTFs are different and are bypassed by the IEM, that individual difference needs to be accounted for to achieve "the same" sound. Right?

That is incorrect. That is the equivalent of saying the orchestra should play and be tuned for each individual differently. We ALL HEAR DIFFERENTLY. That is irrelevant to the band playing on the stage.The source is the source for ALL of us. No competent speaker designer designs for how certain groups of people hear. It makes zero sense to do it for headphones. That is unless you want a colored sound, or less than accurate sound. This is so anti-scientific it is madness.

 

[Jaxx1138]

Not in the normal sense of the word... everyone has their own HRTF but they can be measured, stored, used for processing, etc. I mean, it's "Head Related Transfer Function", not "How Research-subject Truly Feels".

subjective: based on or influenced by personal feelings, tastes, or opinions.

objective: (of a person or their judgment) not influenced by personal feelings or opinions in considering and representing facts.


You can objectively measure HRTF. But it has nothing to do with the headphone or loudspeaker and what they are doing acoustically. It's like seeing the color blue and expressing what it looks like verses measuring the actual frequency of light being reflected from it's surface.

 

[isostasy]

No, you have it backwards. How WE hear has nothing to doing with with the objective performance of the headphone. That is the point. We do not tune speakers by how individuals hear. We should not be doing it with headphones.

I've seen you're already discussing the same topic in the other thread; perhaps they need to be merged, but in the meantime my question is the same: what kind of measurement system would you use for headphones?

Loudspeakers and headphones are different. I feel like you're drawing a false equivalence based on the fact they use the same basic technology (transducers) and we use the same part of our body (ears) to sense the media they reproduce. Despite this, speakers are always 1m+ away in a room with some level of reflection, with your head and body free to move in such a way that what you hear changes, but without modifying any physical aspect of your ear at all. Headphones play left and right directly into each respective ear with no reflection or direction (i.e. as diffuse) and, most importantly, either physically modify or bypass the very thing you are using to hear with!

 

[kemmler3D]

That is incorrect. That is the equivalent of saying the orchestra should play and be tuned for each individual differently. We ALL HEAR DIFFERENTLY. That is irrelevant to the band playing on the stage.The source is the source for ALL of us. No competent speaker designer designs for how certain groups of people hear. It makes zero sense to do it for headphones. That is unless you want a colored sound, or less than accurate sound. This is so anti-scientific it is madness.

Like you say, we all hear differently. To my knowledge, this difference is typically characterized as HRTF or BRTF. Sounds originating some distance from the body are modulated by this transfer function and so a neutral speaker is a neutral speaker for everyone, since those differences in hearing are "equalized" in the brain, for lack of a better term.

My understanding for quite some time now has been that headphones and IEMs in particular bypass the HRTF via simple proximity to the ear, and therefore a neutral headphone is NOT a neutral headphone for everyone. Therefore, the Harman or other preference curves get close but not 100% of the way.

Am I missing something?

 

[kemmler3D]

subjective: based on or influenced by personal feelings, tastes, or opinions.

OK, can you explain how a transfer function is influenced by tastes and feelings? You create it with microphones.

Second question: if you are correct, how come the Smyth Realizer needs in-ear microphone measurements to work?

Third question: If you are correct, why is the harman curve a curve instead of just a flat line, the way it is for speakers?

 

[Jaxx1138]

OK, can you explain how a transfer function is influenced by tastes and feelings? You create it with microphones.

I am not sure what you are saying here. Microphones just capture sound waves and convert it into an alternating voltage. That is not creating feelings.

 

[Jaxx1138]

Second question: if you are correct, how come the Smyth Realizer works?

That is a spatializer. Using mics on your ears and capturing the necessary individual HRTF filters. This is not relevant to objective metrics.

 

[kemmler3D]

I am not sure what you are saying here. Microphones just capture sound waves and convert it into an alternating voltage. That is not creating feelings.

You said HRTFs are subjective, but you can capture them with microphones, so I'm wondering why you would say such a thing.

That is a spatializer. Using binaural recordings. This is not relevant to objective metrics.

Incorrect, it's a spatializer effect that uses any recording you want, employing your personal transfer functions for processing. There's a big section on their homepage entitled "Personalized sound based on your unique ears" that I guess you would label as deeply unscientific?

 

[Jaxx1138]

Like you say, we all hear differently. To my knowledge, this difference is typically characterized as HRTF or BRTF. Sounds originating some distance from the body are modulated by this transfer function and so a neutral speaker is a neutral speaker for everyone, since those differences in hearing are "equalized" in the brain, for lack of a better term.

My understanding for quite some time now has been that headphones and IEMs in particular bypass the HRTF via simple proximity to the ear, and therefore a neutral headphone is NOT a neutral headphone for everyone. Therefore, the Harman or other preference curves get close but not 100% of the way.

Am I missing something?

All this means is that IEM's will have a different transfer function in order to be correct. It does not change the fact that how we individually hear is irrelevant to the objective metrics of the IEM.

 

[Jaxx1138]

You said HRTFs are subjective, but you can capture them with microphones, so I'm wondering why you would say such a thing.


Incorrect, it's a spatializer effect that uses any recording you want, employing your personal transfer functions for processing. There's a big section on their homepage entitled "Personalized sound based on your unique ears" that I guess you would label as deeply unscientific?

I do not believe you understand the difference between their marketing and the actual science behind how it works.

 

[isostasy]

I am not certain at this point. But I believe one that measures the headphone and not how humans hear is imperative to good objective metrics. I think that a some sort of a flat plane for a headphone (not that simplified though) and a standard coupler for a IEM's(modified from the current standards). I do not know the answer without the resources to conduct all the experiments needed to complete the research.

I'm replying here to keep everything in one place as the topic is the same in both threads.

I think therein lies the problem... a flat plane coupler is a sort of head simulator, just not one that's anything much like a human head. You're still simulating a head with an ear by virtue of coupling the headphone to something because we know we have to do this due to free field measurements being no use. Only, your proposed head simulator has a flat surface, nothing like the outer ear, and I'm assuming you'd have the microphone flush with the flat surface.

I'm not sure I understand how your proposal for an IEM coupler would change anything r.e. the above discussion.

 

[kemmler3D]

I do not believe you understand the difference between their marketing and the actual science behind how it works.

Well, by all means, explain it to this poor victim of overly effective marketing.

 

[Jaxx1138]

Well, by all means, explain it to this poor victim of overly effective marketing.

It's a simple metric using mics on your ears to derive your individual HRTF's combined with the room convolution of a particular playback system in a certain room. It takes those filters and applies them to all music you play through their DSP box. It equalizes the sound and adds the binaural cross correlation that is absent in headphone playback. That is a super simplified version of what it is essentially doing.

 

[RandomEar]

This statement is incorrect. they are purely subjective.

Two posts later you state the opposite. This is just ridiculous. It can be measured and modeled (cmp. the linked paper in my last post), it is an objective characteristic.

We do not tune a loudspeaker to how an individual hears. Why would you think we would do it for a headphone.?

I have explained my understanding of why this is necessary, but you simply ignore it and continue to provocatively ask me to do it again. I see no use in that.

Would you believe an orchestra should be tuned to how anyone individual hears?

I don't think you are seriously interested in a productive discussion anymore. Have a nice day.

 

[Jaxx1138]

I'm replying here to keep everything in one place as the topic is the same in both threads.

I think therein lies the problem... a flat plane coupler is a sort of head simulator, just not one that's anything much like a human head. You're still simulating a head with an ear by virtue of coupling the headphone to something because we know we have to do this due to free field measurements being no use. Only, your proposed head simulator has a flat surface, nothing like the outer ear, and I'm assuming you'd have the microphone flush with the flat surface.

I'm not sure I understand how your proposal for an IEM coupler would change anything r.e. the above discussion.

That is the problem here. Noticing that the current method is failing does not mean that I have all the solutions. I need to conduct research in order to resolve much of this. But it is easy to see our current methods are not working effectively.

 

[Jaxx1138]

Two posts later you state the opposite. This is just ridiculous. It can be measured and modeled (cmp. the linked paper in my last post), it is an objective characteristic.


I have explained my understanding of why this is necessary, but you simply ignore it and continue to provocatively ask me to do it again. I see no use in that.


I don't think you are seriously interested in a productive discussion anymore. Have a nice day.

OK, thanks for your time. Even though I believe you are intentionally misunderstanding the obvious.

 

[Gibsonian]

Gather your resumes with the help of specs. Use ears for the final interview/selection That’s the way to go chaps if you enjoy your tunes as much as I do

 

[kemmler3D]

It's a simple metric using mics on your ears to derive your individual HRTF's combined with the room convolution of a particular playback system in a certain room. It takes those filters and applies them to all music you play through their DSP box. It equalizes the sound and adds the binaural cross correlation that is absent in headphone playback. That is a super simplified version of what it is essentially doing.

You missed the part about head tracking, but that seems about right to me.

Now, why on earth do they need to derive an individual's HRTFs if, as you say:

The source is the source for ALL of us. No competent speaker designer designs for how certain groups of people hear. It makes zero sense to do it for headphones.

If headphones could be truly neutral without needing to account for individual differences, spatialized stereo would work properly for everyone with no mics or special processing required.