IEMs bypass HRTF?
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sphinxvc

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I'm wondering if anyone has any information on this.  Given that IEMs sit deep in the ear canal, I've always suspected that they bypass HRTF to a good degree.  So it might be possible for two people with drastically different HRTFs to perceive the same FQ response with deep-set IEMs / as opposed to full-size cans or speakers. 
 
Of course, two different brains may perceive the same sound in two different ways, but for the sake of this argument, it's easier to keep that possibility aside for now.
 
What do you all think?  
 
 
 
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nikongod

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Ignoring the "what does red look like" question :wink:
 
I would GUESS that IEMs make a HRTF more important than full sized headphones.
 
IEM's isolate the inner ear from FR changes an resonances caused by the outer ear, which is a large part of what an HRTF compensates for. 
 
I got a kind of wishy washy answer about whether the JH3a could be programmed for HTRF when I asked in Chicago :frowning2: 
 
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jcx

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I take HRTF to mean the whole amplitude, phase vs frequency response variation, cross coupling from sound waves interacting with ears, head, shoulders - including head angle and sound source angles - it has a lot more dimensions than just a single frequency response at each ear
 
the example of some improvement with crossfeed circuits, plugins immediately shows that cross couping frequency response is significant
 
given the extra dimensionality of "HRTF" I claim no headphone does a particularly good job; iem don't even have the poor  "natural crossfeed" of open back headphones, no headphone can change the frequency response as your head moves
 
the Smyth SVS Realizer does add a sensor, processing for a range of head angle changes but the particular in ear calibration/measurement of HTRF and headphone response they use doesn't work with iem http://smyth-research.com/technology.html
 
as far as perceptual "flat" response with iem you could try http://www.linkwitzlab.com/reference_earphones.htm
 
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MrGreen

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Hello, HRTF is something that is applied to speakers - it is the "coloration", our heads give to a dead-flat speaker, and indeed real life. In essence, it is the frequency curve we are accustomed too, and the one our brain relies on. Disruptions to this, for example, if you have a very bad cold, Eustachian tube dysfunction or sudden hearing loss, can greatly affect your balance (controlled by the inner ear) is disturbed, often through vertigo, as well as your sense of "place" based on stereopositioning of frequencies.

Canalphones actually require a different HRTF function being applied to them, because, I guess you could say they bypass all of it, except the internal canal. A downside to canalphones is the occlusion effect; which is the effect you get when you plug your ears, speak and hear your own voice booming in your head.

You can google around and have a look at target curves for canalphones vs regular headphones (Moller is a good source). You can also see a diffuse field target curve in isolation at the etymotic website.
 
:)
 
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sphinxvc

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Quote:
Ignoring the "what does red look like" question :wink:
 
I would GUESS that IEMs make a HRTF more important than full sized headphones.
 
IEM's isolate the inner ear from FR changes an resonances caused by the outer ear, which is a large part of what an HRTF compensates for. 
 
I got a kind of wishy washy answer about whether the JH3a could be programmed for HTRF when I asked in Chicago :frowning2: 
 
Quote:
I take HRTF to mean the whole amplitude, phase vs frequency response variation, cross coupling from sound waves interacting with ears, head, shoulders - including head angle and sound source angles - it has a lot more dimensions than just a single frequency response at each ear
 
the example of some improvement with crossfeed circuits, plugins immediately shows that cross couping frequency response is significant
 
given the extra dimensionality of "HRTF" I claim no headphone does a particularly good job; iem don't even have the poor  "natural crossfeed" of open back headphones, no headphone can change the frequency response as your head moves
 
the Smyth SVS Realizer does add a sensor, processing for a range of head angle changes but the particular in ear calibration/measurement of HTRF and headphone response they use doesn't work with iem http://smyth-research.com/technology.html
 
as far as perceptual "flat" response with iem you could try http://www.linkwitzlab.com/reference_earphones.htm
 
Jcx, I'm indeed just talking about the outer ear's effect on frequency response (or tonal balance) as opposed to something like sound localization.  Nikongod, it makes sense that HRTF is more important in IEMs even though the outer ear's effects are bypassed, thanks for your insight.
 
 

Quote:
Hello, HRTF is something that is applied to speakers - it is the "coloration", our heads give to a dead-flat speaker, and indeed real life. In essence, it is the frequency curve we are accustomed too, and the one our brain relies on. Disruptions to this, for example, if you have a very bad cold, Eustachian tube dysfunction or sudden hearing loss, can greatly affect your balance (controlled by the inner ear) is disturbed, often through vertigo, as well as your sense of "place" based on stereopositioning of frequencies.

Canalphones actually require a different HRTF function being applied to them, because, I guess you could say they bypass all of it, except the internal canal. A downside to canalphones is the occlusion effect; which is the effect you get when you plug your ears, speak and hear your own voice booming in your head.

You can google around and have a look at target curves for canalphones vs regular headphones (Moller is a good source). You can also see a diffuse field target curve in isolation at the etymotic website.
 
:)



That's a lot of information, thanks.  Will look at those sources.  
 
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MrGreen

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I should have been more clear, you're adding a different HRTF to blocked canals than headphones. You're not adding their HRTF, perse, you're compensating for the DIFFERENCE between the two HRTF; what is being used, and your natural (i.e. speakers/sounds in life)
 
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