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Absolute Transparency

Chris Kelly

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Here's what I mean. Is it yet possible to mic a room and when the volume of the mic mixer is no louder than your surroundings, not be able to tell you're listening through headphones because of the design of the headphones? If headphones which produce such a phenomenon would cost thousands of dollars, what's the closest I can get to this point for between $300 and $500? I don't care whether over-ear, on-ear, in-ear, open-back, closed-back, the driver is large, medium, or small, dynamic, planer magnetic, marketed for audiophiles, marketed for consumers, marketed for DJs, marketed for gaming, marketed for hearing specialists, marketed for live/professional/recording studio use, wired, Bluetooth, RF wireless, wifi LAN, high impedance, low impedance, AKG, Apple, Audio-Technica, Beyerdynamic, Bose, Cambridge Audio, Creative Labs, Dell, Hifiman, HP, Koss, Onkyo, Oppo, Philips, Pioneer, Samsung, Sennheiser, Shure, Sony, Yamaha, etc..
 

restorer-john

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It's less about the headphones and more about how you place and the type of microphones. For headphone listening, you'd be looking at a dummy head arrangement with controlled levels of crossfeeding in the recording itself.
 

usern

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Sony has something where you take a picture of your ears, then their software should be able to use it for DSP settings for more immersive 3D audio
With 360 Reality Audio certified 12 headphones and the Sony | Headphones Connect app, optimize your experience by analyzing your individual ear shape, and enjoy the ultimate immersive music experience.
They list "certified headphones" there, but it should work with any headphones.
 
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Chris Kelly

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It's less about the headphones and more about how you place and the type of microphones. For headphone listening, you'd be looking at a dummy head arrangement with controlled levels of crossfeeding in the recording itself.
OK. Then when running a sinewave chirp, what headphones show the most equal level throughout the audio spectrum without applying EQ?
 

usern

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Here's Mark Cerny talking about 3D audio (and probably the technology that is used in that 360 reality thing):
 

Doodski

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OK. Then when running a sinewave chirp, what headphones show the most equal level throughout the audio spectrum without applying EQ?

AKG K371​

I don't recommend them due to the construction but they are supposed to sound alright.
 
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Chris Kelly

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And what open-back headphones will also reproduce a sinewave chirp with equal levels throughout the audio spectrum without applying EQ?
 

Doodski

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And what open-back headphones will also reproduce a sinewave chirp with equal levels throughout the audio spectrum without applying EQ?
 
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Chris Kelly

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AKG K371​

I don't recommend them due to the construction but they are supposed to sound alright.
The old famous Harman curve. I know some people like a U-curve or V-curve for music which bass and percussion are more important. Also, some people like what I'm going to call a lowercase n curve or a ^-curve for when speaking and/or singing is/are important. I prefer as much of a --curve (dash-curve) I can get without applying EQ being that not all equipment I use has EQ controls.
 
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Doodski

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The old famous Harman curve. I know some people like a U-curve or V-curve for music which bass and percussion are more important. Also, some people like what I'm going to call a lowercase n curve or a ^-curve for when speaking and/or singing is/are important. I prefer as much of a --curve (dash-curve) I can get without applying EQ being that not all equipment I use has EQ controls.
I prefer as much high frequency EQ/PEQ as I can get.
 
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Sony has something where you take a picture of your ears, then their software should be able to use it for DSP settings for more immersive 3D audio

They list "certified headphones" there, but it should work with any headphones.
Apple scans your head and ears with matrix dot projector as initial setup for the Airpods Pro. Don't know if a plain picture is a good way to do depth deduction from.
 

jae

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What you are describing (within the realm of our understanding and what we can practically control) mostly has to do with matching the frequency response at each eardrum of the signal you would hear in that room with the frequency response of that same very signal at each ear drum while wearing headphones. There's an example of someone doing this here: https://www.audiosciencereview.com/...d-equalization-using-in-ear-microphone.35992/

There are going to be limitations of this with how accurate it can be measured, but if you can get the important audiometric frequencies of 125hz - 8 khz (or up to 16khz if possible) with a decent amount of accuracy, it can sound very convincing. Ideally, I think the measurements would be taken with something like a probe tube microphone like what audiologists use for doing in-ear hearing aid measurements so the whole effect of the canal resonance could be measured at the ear drum.

Headphone itself theoretically doesn't matter as much. Since Harman FR headphones are a representative mean of what people tend to prefer or think is more realistic, I would expect Harman tuned headphones to be probably what one would aim for this purpose anyway. Ideally you want something that has a smooth response and is already close to your HRTF in the condition/position you want to emulate, and also that it does not have inherent "problems" like resonances in critical bands or bands that you might need to drastically EQ. At/under $500, the best bet for a low distortion headphone that has no problem with EQ is the DCA Aeon RT Open/Closed, albeit the out of the box response isn't ideal, but that shouldn't matter much if it needs to be EQ'd anyway. Or virtually any smooth multi-driver IEM (occluding the ear has its pros and cons). Alternatives I would say are DCA Aeon2/Noire at $800, Stealth/Expanse at $4000. If you are on a budget, the K371 or 6XX are probably fine choices too. Funnily enough, these aren't any different from the exact headphones I would suggest to buying headphones in general.

An alternative to actually measuring the response due to your anatomy is doing a kind subjective equal-loudness equalization with a signal in those conditions, for example read this: http://www.davidgriesinger.com/ , where the process is explained with companion software for making it easier to do. https://distortaudio.org/earful.html could also help to generate equal loudness curves. This method could also be used in conjunction with actually taking objective measurements, because limitations of measuring won't be as useful in some bands because psychoacoustic considerations in the low end, and subtle things in the very high end are harder to quantify in certain setups, on top of the fact virtually every adult has some kind of HF hearing loss. Whereas some idiosyncrasies of subtle (but important) features of the ear resonance region may be lost with just a subjective FR matching
 
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Chris Kelly

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What you are describing (within the realm of our understanding and what we can practically control) mostly has to do with matching the frequency response at each eardrum of the signal you would hear in that room with the frequency response of that same very signal at each ear drum while wearing headphones. There's an example of someone doing this here: https://www.audiosciencereview.com/...d-equalization-using-in-ear-microphone.35992/

There are going to be limitations of this with how accurate it can be measured, but if you can get the important audiometric frequencies of 125hz - 8 khz (or up to 16khz if possible) with a decent amount of accuracy, it can sound very convincing. Ideally, I think the measurements would be taken with something like a probe tube microphone like what audiologists use for doing in-ear hearing aid measurements so the whole effect of the canal resonance could be measured at the ear drum.

Headphone itself theoretically doesn't matter as much. Since Harman FR headphones are a representative mean of what people tend to prefer or think is more realistic, I would expect Harman tuned headphones to be probably what one would aim for this purpose anyway. Ideally you want something that has a smooth response and is already close to your HRTF in the condition/position you want to emulate, and also that it does not have inherent "problems" like resonances in critical bands or bands that you might need to drastically EQ. At/under $500, the best bet for a low distortion headphone that has no problem with EQ is the DCA Aeon RT Open/Closed, albeit the out of the box response isn't ideal, but that shouldn't matter much if it needs to be EQ'd anyway. Or virtually any smooth multi-driver IEM (occluding the ear has its pros and cons). Alternatives I would say are DCA Aeon2/Noire at $800, Stealth/Expanse at $4000. If you are on a budget, the K371 or 6XX are probably fine choices too. Funnily enough, these aren't any different from the exact headphones I would suggest to buying headphones in general.

An alternative to actually measuring the response due to your anatomy is doing a kind subjective equal-loudness equalization with a signal in those conditions, for example read this: http://www.davidgriesinger.com/ , where the process is explained with companion software for making it easier to do. https://distortaudio.org/earful.html could also help to generate equal loudness curves. This method could also be used in conjunction with actually taking objective measurements, because limitations of measuring won't be as useful in some bands because psychoacoustic considerations in the low end, and subtle things in the very high end are harder to quantify in certain setups, on top of the fact virtually every adult has some kind of HF hearing loss. Whereas some idiosyncrasies of subtle (but important) features of the ear resonance region may be lost with just a subjective FR matching
I've never heard of DCA nor can afford the DCA models you mentioned. It sounds like they need EQ anyway. Does AKG make any models in the 600 range, or did you mean Sennheiser? I've had experience with the HD 400 PRO, HD 559, HD 560S, and HD 599. I returned the 400 PRO and 560S because I thought upper mids were a little too much with singers and dialog for TV shows and movies sounding more like I was hearing them through a telephone earpiece than in person, with an n-curve or upsidedown v-curve, or ^-curve. I kept the 599, and after eight months, I started to notice a u-curve or v-curve with extra bass and treble. I've had the 559 for a few weeks. A few times, I thought footsteps and background noise in shows and movies have more bass than in real life. I am thinking about auditioning the Sennheiser HD 600 and HD 650 because I've read that they require less EQ to get that transparency I'm seeking than even their 660S, 800S, and820, as well as their 58X and 8XX sold by Drop.
 
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jae

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6XX = https://drop.com/buy/massdrop-sennheiser-hd6xx = equivalent to sennheiser hd650. for $199-230. Drop 58X/580 is also fine too.

DCA Aeon RT = https://danclarkaudio.com/aeon-rt-new-1.html is in the $500 limit you mentioned

Only AKG OE headphones that aren't bad in my opinion are the K371 and maybe the AKG K612/K701/K702 line. IMO the other headphones are a waste of time, especially if you are going to be EQing.

Look and compare frequency response plots, for example on Crinacle's website, of headphones you have already tried to other ones you are interested in so you can see where they differ. If you want an open headphone <$500 I suggest 6XX or DCA RT open, or K371/DCA RT closed if you want a closed pair.
 
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Chris Kelly

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There seems to be a lot of accessibility issues with selling online. So if I am unable to sell the AV gear I won't be using anymore, I might keep my HD 559 and HD 599, and just get the HD 560S. The HD 559 are the warmest, making them good for singers like Andrea Bocelli, Celine Dion, Enya, etc.. The HD 599 have boosted bass and treble, making them good for Classic Rock. The HD 560S have more of a balanced bass, but gives voices the quality of a telephone earpiece. Out of these three, I'm not sure which I'd prefer for Classical music, movies, and TV shows.
 

kemmler3D

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Here's what I mean. Is it yet possible to mic a room and when the volume of the mic mixer is no louder than your surroundings, not be able to tell you're listening through headphones because of the design of the headphones?

Yes, this is possible, but as restorer-john said, if you want to actually do this, it depends a lot more on how the recording is made, than the headphones. It's actually easier to do with IEMs than over-ear.

The whole problem with creating this type of illusion has to do with the shape of your ears. Everything you hear is filtered by your head, shoulders, and ears especially. Your brain uses this filtering to figure out where things are (spatial cues).

Speakers can create spatial cues because the sound still hits your body and ears like anything else.

Headphones really struggle with spatial cues, because suddenly your shoulders, head, and parts of your ears are removed from the equation. By putting the sound source so close to your ear, you bypass a lot of this natural filtering. It's as if your brain is expecting some EQ but you've shut off 2/3 of it. This is why the harman headphone curve is not nearly flat. We have to add back some of that natural "EQ".


However, the process of "adding back" the filtering from our ears and heads etc. is a very imperfect science, unless you have detailed scans of your ears and a very good spatial audio software.

One way to get around this - make the recording in the room using a binaural mic setup with little models of your ears in front of the microphones. Then you listen on IEMs and it will sound perfectly real, as you describe. Another way - get an HRTF filter of your own head and ears, and apply it to a binaural recording made without fake ears attached. Last way - make a binaural recording yourself, with the mics IN your ears. (yes, people do this.) It will sound basically real when you listen on IEMs.

To achieve this with over-ear headphones, you're up against a tricky problem, because the sound wave will never hit your ear quite right, to totally fool your brain. This is why auditioning headphones is really important if you want a true illusion. The radiation pattern of sound inside the cup varies (some are angled, there may be lobing in there, who knows), and its interaction with your own ear cannot be predicted.

So in terms of raw performance most cans in this thread are good enough to do what you're talking about. HOWEVER, none of them are likely to create a true 3D illusion for you in the way you describe.

If you are literal and serious about your goal, my advice is to get a binaural recording or three (raw, with your ears, with jig), take the recordings to AXPONA or similar, and demo as many headphones as you can. You may get lucky and find the magic set for your ears.

If you just want headphones that are good enough to create perfect realism in theory then I think there are good recommendations here already. I would suggest finding some with really low distortion so you have a lot of flexibility to EQ.
 

LTig

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Last way - make a binaural recording yourself, with the mics IN your ears. (yes, people do this.) It will sound basically real when you listen on IEMs.
I did this once im my student days using a Sennheiser HD430 headphone as microphone (yes, this works, there was just some hum due to the non shielded cable). Playback while sitting at the same spot was absolutely real.
 
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Chris Kelly

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I am sight impared and can't decipher graphs. Does amirm show graphs from test results without EQ? If so, which is flatter/straighter, the Sennheiser HD 560S, the Sennheiser HD 600, or the Sennheiser HD 650? Also, from what I understand, amirm didn't follow his standard testing procedure when reviewing the HD 600. I didn't go through the whole thread. So I don't know if he updated it later.
 
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Doodski

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Does amirm show graphs from test results without EQ?
Yes, EQ/PEQ is not shown in the graphs.
I am posting the graphs so we can see them and discuss them more easily for us. I think in it's raw form without EQ/PEQ changes that the HD560S has the better response graph.
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