Proximity effect and the psychoacoustically wrong target FR curves

[Deleted member 21219]

May I suggest that it is because your wonderful headphones correctly adjust for the proximity effect in its tuning, and that you wouldn't have felt like you were in a concert hall if your headphones were tuned to the DF target?

I think @IAtaman hit the nail on the head with "acoustic loading" as a reason for the difference. Take a small transducer (such as a 4" full-range) that is "tuned" for the box into which it is inserted, and take it out. Lay it on the table. The same difference in sound will occur as a pair of headphones, and yet it's not proximity effect. It's loading and cancellation .... nothing to do with the brain.

Jim

 

[NTK]

Or both! Try a different exercise, where the difference in volume wouldn't be as drastic so the impedance of the transducer isn't a concern: hold one of the earcups close to your ear but without creating a seal. Now hold it just a tad further while increasing the volume on the amp to match the perceived volume you hear. Does it get less bassy?

It is because for headphone listening, we are listening in the acoustic near field (not to be confused with the non-acoustician use of the term). That's why sealing makes huge differences for headphones, but not for loudspeakers listening in rooms.

Reference: https://www.win.tue.nl/~sjoerdr/papers/boek.pdf

 

[thanrl]

But... why? If we talking about "traditional" headphone design, in which drivers are parallel to our ears without any angling, it literally kills any spartial cues, since soundwaves fall into our ear canal under constant angle, which differs drastically from 60 degrees (for stereo), that we usually use for mixing and mastering music

I think you are close to where I'm getting at. My point is that since our brain knows we are wearing headphones, it naturally demands spatial cues of a sound being played so closely, one of which is the proximity effect. Other spatial cues that convey the sense of space in the music need to be correctly simulated now that the driver is parallel to the ears instead of 60 degrees, yes, but they are complicated by the fact that our brain is simultaneously "confused" by the fact a concert hall is emulated by a sound source so close to the ears. Therefore, adjustment to the said simulation needs to be made to compensate for this "confusion."

 

[thanrl]

I think @IAtaman hit the nail on the head with "acoustic loading" as a reason for the difference. Take a small transducer (such as a 4" full-range) that is "tuned" for the box into which it is inserted, and take it out. Lay it on the table. The same difference in sound will occur as a pair of headphones, and yet it's not proximity effect. It's loading and cancellation .... nothing to do with the brain.

Jim

It is because for headphone listening, we are listening in the acoustic near field (not to be confused with the non-acoustician use of the term). That's why sealing makes huge differences for headphones, but not for loudspeakers listening in rooms.

Reference: https://www.win.tue.nl/~sjoerdr/papers/boek.pdf

I'm surprised by that folks are rejecting the existence of proximity effect. Do you hear the proximity effect? If you do, why wouldn't it impact the way you perceive sound played from a headphone?

 

[kemmler3D]

why wouldn't it impact the way you perceive sound played from a headphone?

Proximity effect is real and probably affects headphone sound quite a bit.

The thing is, the effect has been real from the beginning, and headphones have already been designed to compensate for it (and other psychoacoustic distortions) over time. It's one of the reasons that "flat" HP responses are not even remotely flat. You would probably say it's been empirically solved, rather than by theory, but we don't seem to be suffering from it.

From the other direction, what would uncompensated loudness effect on headphones be like?

To use your example, headphones would be usable as nearfield speakers if they were loud enough. Just lay them on the table and turn them up... As you note, they are not used this way. They don't sound right at a distance. This shows us that proximity effect is already implicitly solved in a good headphone tuning.

 

[thanrl]

Proximity effect is real and probably affects headphone sound quite a bit.

The thing is, the effect has been real from the beginning, and headphones have already been designed to compensate for it (and other psychoacoustic distortions) over time. It's one of the reasons that "flat" HP responses are not even remotely flat. You would probably say it's been empirically solved, rather than by theory, but we don't seem to be suffering from it.

Thank you. This is exactly what I'm try to say. Sorry if I'm doing a poor job. Non-native English speaker here.

From the other direction, what would uncompensated loudness effect on headphones be like?

To use your example, headphones would be usable as nearfield speakers if they were loud enough. Just lay them on the table and turn them up... As you note, they are not used this way. They don't sound right at a distance. This shows us that proximity effect is already implicitly solved in a good headphone tuning.

DF I suppose? I am in complete agreement with you. I'd add that like everything psychological, different brains demand different proximity effects. The degree of proximity effect would also be different on headphones vs earbud vs IEM. The inductive science is mostly done, i.e. by now we all know what our preferred sound in headphones are. The deductive science, however, has made no progress since the DF curve.

 

[kemmler3D]

Thank you. This is exactly what I'm try to say. Sorry if I'm doing a poor job. Non-native English speaker here.

DF I suppose? I am in complete agreement with you. I'd add that like everything psychological, different brains demand different proximity effects. The degree of proximity effect would also be different on headphones vs earbud vs IEM. The inductive science is mostly done, i.e. by now we all know what our preferred sound in headphones are. The deductive science, however, has made no progress since the DF curve.

Makes sense. I guess headphones are also measured with proximity effect too... and so comparing mic vs. ear proximity effect might be revealing in terms of headphone tunings...

 

[Geert]

I'm surprised by that folks are rejecting the existence of proximity effect. Do you hear the proximity effect? If you do, why wouldn't it impact the way you perceive sound played from a headphone?

What you refer to as the proximity effect is not an effect of the ears or brain, the reason is that most sound sources are more omni directional at low frequencies so they the lows loose more intensity at increased distance.

Our brain doesn't necessarily expect more lows at a closer distance. If you eq a set of speakers at 3m to sound neutral at the listening position and eq a second pair ar 12m to sound neutral then they will both sound fine.

 

[thanrl]

the lows loose more intensity at increased distance.

Our brain doesn't necessarily expect more lows at a closer distance

Isn't that a bit contradictory?

 

[Salt]

I use inears (vulgo stethoscope) for almost 40 years almost daily and may state: without most possible proximity to the tympanon they sound like a mess , but did make no ABX yet, may be wrong .

And seriously: of course the smoky sound of a beloved voice sounds just more 'chesty' when close to ones ... ehem ... ear .... than 10 feet away .

Ok, third attempt: there may be some subjective approaches in the discussion and some scientific
basics, but let me be subjective now: the DSP between the ears is a competent mediator between (not only a singular) worlds.
Just performing a double blinded randomized test with myself and listening to music via HP (Highendest Sennheiser 450 BT ) to well known music from listening by speakers before and I can switch from 'inbetweenthehead' to 'stereopanorama' as I like, just recalling memories? or interpretation of HP sound with different iterpretation of sound waves?
Human brain is most of the time a fascinating flawless working system to support comfort in high fidelity

 

[Geert]

Isn't that a bit contradictory?

No, why, would it? It only means that a set of speakers further away in general needs more lows to deliver a neutral sound at the listening position.

If we would go with your proximity story and adopt the target frequency curve to the distance of the speakers, than what happens if you close your eyes so you don't know at what distance the speakers are? Does the sound then suddenly change?

 

[thanrl]

No one is rejecting the existence of the proximity effect. We simply don't interpret it or use it the way you do.

As for the sound of someone whispering in your ear, that has as much to do with the acoustic loading of their body as it does the nearness to your eardrum. Take a small transducer to emit a low-SPL signal directly to the side of your head, then the top, the back and the front, all at the same (very close) distance. Then repeat the same exact test, only put the small transducer in the middle of a piece of plywood 8" in diameter. It will sound much different. That difference has nothing to do with the anticipation of your brain, or a proximity effect, and keeping the distance the same will prevent variations in distance form muddying the results. The only difference is loading to the front of the transducer.

I wonder whether sighted bias is skewing your results. There has to be a way to remove sighted bias from a test of your hypothesis ...... no?

Jim

Sorry, I am not following. What do you mean by the acoustic loading of a person's body? I thought a person whispering into your ears 1 inch away should sound a lot more bassy than 2 inches away, yet the difference in distance is small enough that the person doesn't really need to change the volume or the tone in which they whisper.

A different exercise is to tap your fingers next to your ears. As you approach and enter your outer ear, the distance at which we wear the headphones, the sound will be drastically more bassy.

 

[Deleted member 21219]

Sorry, I am not following. What do you mean by the acoustic loading of a person's body? I thought a person whispering into your ears 1 inch away should sound a lot more bassy than 2 inches away, yet the difference in distance is small enough that the person doesn't really need to change the volume or the tone in which they whisper.

A different exercise is to tap your fingers next to your ears. As you approach and enter your outer ear, the distance at which we wear the headphones, the sound will be drastically more bassy.

I deleted my post, as it was not clear at all. I apologize for that. When I get my thoughts clearly in order, I'll address the issue again.

However ... you can trust that no one is rejecting the existence of a proximity effect.

Jim

 

[thanrl]

I deleted my post, as it was not clear at all. I apologize for that. When I get my thoughts clearly in order, I'll address the issue again.

However ... you can trust that no one is rejecting the existence of a proximity effect.

Jim

No worries! I look forward to learning more about acoustic loading.

 

[thanrl]

No, why, would it? It only means that a set of speakers further away in general needs more lows to deliver a neutral sound at the listening position.

If we would go with your proximity story and adopt the target frequency curve to the distance of the speakers, than what happens if you close your eyes so you don't know at what distance the speakers are? Does the sound then suddenly change?

I was able to parse what you are trying to say. Everything you are saying is true, but I am not concerned about bass standing wave or room treatments. My claim is that our ears are very good at picking up the distance cues. When we close our eyes, we most likely can tell distances apart. They might not do very well picking up the difference between speakers 6 feet and 7 feet away (especially when the speaker is loud and of good quality), but they can easily tell the difference between 1 inch and 6 feet away, or the difference between 1 inch and 2 inches away. Therefore, if a sound source playing 1 inch away is trying to emulate the sound of a sound source playing 6 feet away, we'd be able to tell. Do you agree?

 

[Philbo King]

IMHO
There is a huge difference between transmitting sound into a tube (your ear canal) and lauching into free space.

If you want to pursue this idea, you need to delve into the acoustic physics of each to get a basic grasp of what is going on for each scenario.

 

[Deleted member 21219]

I deleted my post, as it was not clear at all. I apologize for that. When I get my thoughts clearly in order, I'll address the issue again.

OK ... I did a little experiment. It was not rigorously controlled, and my measurements were not necessarily exact. Here's what I found:

I took a piece of plexiglass about the size of the head and upper chest area of a person. (I have one that has been laying around for many years.) First I snapped my fingers about 2 inches from my ear canal, but in free space. Than I moved the plexiglass close to my head, hopefully simulating the body of someone whispering to me. I could hear a lower-frequency component being increased.
Then I did the same thing, but with my fingers snapped only about an inch from my ear canal. This was difficult, because getting my fingers in there, snapping, and moving the plexiglass was almost like a circus balancing act; it took great care and many repetitions.
However, in the end, the result was similar. There was an increased lower-frequency component. Although it was not quite as noticeable as when I had the snap at two inches from my ear canal, it was very close.

It seems that there is a reinforcement of lower frequencies as a larger object (like the upper body of someone whispering to us) is brought close to our ears. I call this "acoustical loading".

That's probably the wrong term. However, the effect is real. So when you said ...

I thought a person whispering into your ears 1 inch away should sound a lot more bassy than 2 inches away, yet the difference in distance is small enough that the person doesn't really need to change the volume or the tone in which they whisper.

... you may have been correct, but to a lesser degree than what you suspect.

That's my story and I'm stickin' to it!

Jim

 

[Galliardist]

(If the music did NOT have these ambient cues included .... well, then I admit that all bets are off. It would be interesting to experiment and find out, though.)

Jim

Relatively easy, just download and play a MIDI file, best with some bass content. No cues.

Interestingly, the difference remains, but by using another file with only treble content, you can show that the main cause is just that the headphones don’t put out enough bass when on the table.

 

[Geert]

I was able to parse what you are trying to say. Everything you are saying is true, but I am not concerned about bass standing wave or room treatments.

I didn't mean room eq when talking about eq, I was talking about EQ-ing for the loss of low frequencies due to increased distance.

My claim is that our ears are very good at picking up the distance cues. When we close our eyes, we most likely can tell distances apart.

They pick up the change in frequency response (due to the directivity that changes with frequency and air resistance) or direct versus reflected sound levels. A microphone could also identify these. Correct for these factors and your ears won't be able to tell the difference in distance.

Therefore, if a sound source playing 1 inch away is trying to emulate the sound of a sound source playing 6 feet away, we'd be able to tell. Do you agree?

In theory, no. In open air, no. However, in a room it would be difficult to neutralize the changing direct versus reflected sound levels. Don't see how that supports your theory that headphones target frequency responses are wrong because our brain knows the transducers our nearby.

 

[thanrl]

I didn't mean room eq when talking about eq, I was talking about EQ-ing for the loss of low frequencies due to increased distance.



They pick up the change in frequency response (due to the directivity that changes with frequency and air resistance) or direct versus reflected sound levels. A microphone could also identify these. Correct for these factors and your ears won't be able to tell the difference in distance.



In theory, no. In open air, no. However, in a room it would be difficult to neutralize the changing direct versus reflected sound levels. Don't see how that supports your theory that headphones target frequency responses are wrong because our brain knows the transducers our nearby.

I think we are in agreement with the premise, that room acoustics is a major barrier to a successful simulation of speaker-in-a-room through ear-side transducers. (I'm also aware that near-field monitoring requires less bass; not sure how it adds to the discussion)

What I'm trying to do is to draw a conclusion: Even if a headphone has a theoretically perfect FR simulation of a speaker-in-a-room (i.e. the DF target), the lack of room acoustics and the headphone's physical contact can together distract the ear and the brain from being immersed in said simulation. Now that the brain recognizes that the sound source is nearer than a speaker-in-a-room, yet has the FR of speaker-in-a-room, it is "confused". Simulating a proximity effect (on top of the simulation of speaker-in-a-room), as I hypothesize, reduces the degree of "confusion".

I am trying to give a theory as to why headphone preference targets are warmer than the DF target, even if the DF target is bass-corrected. I am not rejecting preference targets, but trying to derive them from combining DF target and proximity effect.