Headphones and the Harman target curve

[Cars-N-Cans]

You mean the other way round, surely? If the headphones produce the same bass response at the ear, it will seem as though they have less bass due to lack of tactile feedback, not 'boosted'?

From my experience, I easily listen to speakers 10 dB louder than headphones due to the tactile feedback. Without the context, the presentation is much different. On the floor system the SPL level gets up to 110-115 dB in the bass region. In cars this (used to be) 135+ where my SPL meter stops. If I put a set of headphones on at 110-115 dB, it just seems like too much and the headphones sound too loud. The tactile sensations add context and an additional dimension to the experience. This and most modest-size speakers will have a response that starts to nose-dive below around 60 Hz without a sub, and even that can be generous in many cases. Combine these together with large over-ear headphones often having bass extension down into 20Hz and below and this could potentially throw people off if they are not accustom to it. If you usually use some small speakers or bookshelfs on a set of stands where the in-room response plummets below 80Hz, having a large set of headphones rattling around on your head could easily give an impression of an overly-excessive bass response.

 

[Cars-N-Cans]

You mean the other way round, surely? If the headphones produce the same bass response at the ear, it will seem as though they have less bass due to lack of tactile feedback, not 'boosted'?

As an additional wrinkle, headphones likely still have a different overall transfer function than speakers due to the headphones delivering 100% direct sound at all times, whereas the speakers will have a portion of their sound being reverberant like we are normally used to with actual things we hear. The imaging is certainly not the same, and on conventional stereo systems it can be quite different. The Harman target addresses all of these factors by implicitly rolling them into one curve to give the most neutral presentation for the majority of listeners. Since its based on controlled listening tests and is influenced by our physical biology, there is no easy way to say where each and every part of the target fully originates from. I think generally researchers likely have a very good idea, but there will always be some error bars involved.

 

[Robbo99999]

To add to Sean’s comments, I think another thing is the lack of tactile bass. On a speaker system that can be A/B’d with headphones simultaneously, the lack of tactile feedback makes it seem like the headphones have boosted bass. It’s not until each is level matched to a level low enough to take the bass out of the equation that I realize they are in fact the same. And one has to remember that the speaker is shooting for tonally neutral sound reproduction to start with. If I record sound using a decent mic array and listen to it back thru the headphones, it’s clear they are reproducing the sound tonally. This may not be so for all users, but it at least shows for most it will provide a perceptually flat response.

I don't think it's that valid listening to a recording of your speakers over your headphones - the reason being is that you've already got the downslope of the room being recorded in your mics, and then you've got your Harman Curve Headphones that also have the room "simulated" by it's downslope too, so the end result is that you're listening to the downslope of two "rooms" in your headphones in that experiment you mention. I also agree with @isostacy 's reply to you re headphone & speaker (tactile) bass perception, so that doesn't quite tally either - but in your experiments you'd have to be sure that both the headphones & speakers extend to the same depth in the bass (which you alluded to in a later post).

 

[Cars-N-Cans]

I don't think it's that valid listening to a recording of your speakers over your headphones - the reason being is that you've already got the downslope of the room being recorded in your mics, and then you've got your Harman Curve Headphones that also have the room "simulated" by it's downslope too, so the end result is that you're listening to the downslope of two "rooms" in your headphones in that experiment you mention. I also agree with @isostacy 's reply to you re headphone & speaker (tactile) bass perception, so that doesn't quite tally either - but in your experiments you'd have to be sure that both the headphones & speakers extend to the same depth in the bass (which you alluded to in a later post).

No, that's not what I was saying. As I stated, I am A/B'ing the actual headphones and speakers. They are on a separate sources playing the same material simultaneously. I can thus mute the speakers, and listen to the headphones, and switch back. I also have control over the loudness of both at the same time. I don't know who would think listening to speakers recorded by a conventional microphone over headphones is really valid, and its even less valid with a single-channel omni since it records EVERYTHING and condenses it down to mono. The only scenario that is accepted as being valid is when there are calibrated microphones in a dummy head for binaural recording. If I recall Dr. Toole mentions such a test utilizing this in his book Sound Reproduction, but its been some time since I read it. On top of that, much of the imaging of speakers (and headphones) comes from the auditory center processing the various cues in the recording. Microphones and recording equipment do not have brains, obviously. It only records what the transducer picks up. Without a dummy head, the recording can maybe give some idea of the tonality, but outside of that not much else could be said.

Edit: And as a parting thought, since a neutral speaker in a semi-reflective room is stated as being one of the references for the Harman target, using a speaker or speakers and repeating the experiment in an environment that approximates this better at least be somewhat repeatable, or that's not the scientific method. Granted, to be totally valid I would need Harman's listening room and speaker(s) used for said references, but given how close they are in my setups, I would say its a reasonably valid ad-hoc test to do.

 

[Cars-N-Cans]

I don't think it's that valid listening to a recording of your speakers over your headphones - the reason being is that you've already got the downslope of the room being recorded in your mics, and then you've got your Harman Curve Headphones that also have the room "simulated" by it's downslope too, so the end result is that you're listening to the downslope of two "rooms" in your headphones in that experiment you mention.

And to be clear, this is a near-field system, so the imaging is very much vis-à-vis, just to answer any more potential misunderstandings. Some may not agree with this, and fine. But the lack of tactile bass is a big difference, as is the IHL that often occurs with headphones when you don't have any sort of additional processing, which makes sense. Its just shoving the sound down your ear canals. There's no opportunities for it to interact with either your head or pinnae outside of maybe Sennheiser's EAR greebling in the 560S or having large sloped planar drivers.

 

[posvibes]

I have been listening to my old Stax Lambda headphones (normal bias) and they are a little sharper in the highs and tend to grate on my ears after a short while. So hunting around the internet for a possible EQ setting I came across a 1500hz peak filter, -5dB and a Q of 2 and it seems to have done the trick. But I don't know if it is my imagination but does a change in EQ settings lead to instrument displacement in the "soundscape"

 

[Cars-N-Cans]

I have been listening to my old Stax Lambda headphones (normal bias) and they are a little sharper in the highs and tend to grate on my ears after a short while. So hunting around the internet for a possible EQ setting I came across a 1500hz peak filter, -5dB and a Q of 2 and it seems to have done the trick. But I don't know if it is my imagination but does a change in EQ settings lead to instrument displacement in the "soundscape"

It can since it will have an effect on the region of the headphone's response where a lot of the spatial cues lie. This is why headphones "open up" and can have spatial effects where there were none in HP reviews on ASR once PEQ has been applied per measurements.

 

[posvibes]

where a lot of the spatial cues lie

It's quite extraordinary, it is like listening to an alternative mix. Some previously dominant notes have retreated back into the mix etc. The PEQ settings from the web were actually for the Stax Lambda Signature model, but I figure close enough is good enough, as Harman Curving for Stax as I understand it is like " trying to shovel smoke with a pitchfork in the wind". This setting has taken away the screeching highs and subjectively taken away the individual bass sound for something a little more generic, but still wholly more enjoyable to me.

 

[Robbo99999]

No, that's not what I was saying. As I stated, I am A/B'ing the actual headphones and speakers. They are on a separate sources playing the same material simultaneously. I can thus mute the speakers, and listen to the headphones, and switch back. I also have control over the loudness of both at the same time. I don't know who would think listening to speakers recorded by a conventional microphone over headphones is really valid, and its even less valid with a single-channel omni since it records EVERYTHING and condenses it down to mono. The only scenario that is accepted as being valid is when there are calibrated microphones in a dummy head for binaural recording. If I recall Dr. Toole mentions such a test utilizing this in his book Sound Reproduction, but its been some time since I read it. On top of that, much of the imaging of speakers (and headphones) comes from the auditory center processing the various cues in the recording. Microphones and recording equipment do not have brains, obviously. It only records what the transducer picks up. Without a dummy head, the recording can maybe give some idea of the tonality, but outside of that not much else could be said.

Edit: And as a parting thought, since a neutral speaker in a semi-reflective room is stated as being one of the references for the Harman target, using a speaker or speakers and repeating the experiment in an environment that approximates this better at least be somewhat repeatable, or that's not the scientific method. Granted, to be totally valid I would need Harman's listening room and speaker(s) used for said references, but given how close they are in my setups, I would say its a reasonably valid ad-hoc test to do.

You said "If I record sound using a decent mic array and listen to it back thru the headphones, it’s clear they are reproducing the sound tonally." What did you mean by that then?

 

[Cars-N-Cans]

You said "If I record sound using a decent mic array and listen to it back thru the headphones, it’s clear they are reproducing the sound tonally." What did you mean by that then?

Do you listen to recorded music using headphones?

 

[Robbo99999]

Do you listen to recorded music using headphones?

Hmm, you're not making this very simple or clear, it's a bit like getting blood out of a stone, ha! So when you said "If I record sound using a decent mic array and listen to it back thru the headphones, it’s clear they are reproducing the sound tonally." then you simply meant that you were listening to recorded music you can stream or buy rather than recording "something" yourself? (Recap for readers: Your original post made it out that you were recording your own speakers.)

 

[Cars-N-Cans]

Hmm, you're not making this very simple or clear, it's a bit like getting blood out of a stone, ha! So when you said "If I record sound using a decent mic array and listen to it back thru the headphones, it’s clear they are reproducing the sound tonally." then you simply meant that you were listening to recorded music you can stream or buy rather than recording "something" yourself? (Recap for readers: Your original post made it out that you were recording your own speakers.)

Are you daft, mate? My post was reasonably clear and by sound I literally meant sound. If you misread my post, fine. But at least don't continue to grasp at straws afterwards.

Re: The recording, I went and recorded sounds (can be anything like birds and other nature sounds, fountain at the park, etc.) and then play them back thru the headphones as a simple, fun experiment. This is no different than listening to music thru headphones. We have recorded material that is being reproduced. Make sense, now? Edit: And yes there will obviously be mixing. But the core thesis is the same. They should tonally reproduce what was recorded.

 

[Robbo99999]

Are you daft, mate? My post was reasonably clear and by sound I literally meant sound. If you misread my post, fine. But at least don't continue to grasp at straws afterwards.

Re: The recording, I went and recorded sounds (can be anything like birds and other nature sounds, fountain at the park, etc.) and then play them back thru the headphones as a simple, fun experiment. This is no different than listening to music thru headphones. We have recorded material that is being reproduced. Make sense, now?

Hey, hey, no need for the insults - I'm just trying to understand you. You've eventually been able to make yourself understood though. Although I don't agree with your idea of recording bird sounds and then listening to them in your headphones as an accurate way of judging their tonality - instead you'd need to listen to some spectrally dense music that covers most of the frequency range to properly judge good tonality.

 

[Cars-N-Cans]

Fine and fair enough. My apologies. But you very much gave the impression of being on a "fact-checking" mission without stopping to acknowledge that you had misinterpreted what I had said from the outset. I certainly don't fault people for making mistakes. We all do it. But it helps to at least indicate on some level that there was a misunderstanding from the outset with subsequent replies. I'm sure many of us don't mind elaborating. But this is just a text forum, so there is no context beyond what can be gleaned from the characters on the screen. Normally there would be emotions and tone of voice to indicate that someone is not following during an actual conversation. Edit: And please at least try not to strawman others arguments. In regards to (can be anything like birds and other nature sounds, fountain at the park, etc.), it's clear I was just providing that as an example to help you get some idea of what I meant. Not as an absolute statement. I think most of us know that there is a need to use a wide variety of content to accurately assess tonality.

 

[Cars-N-Cans]

Although I don't agree with your idea of recording bird sounds and then listening to them in your headphones as an accurate way of judging their tonality - instead you'd need to listen to some spectrally dense music that covers most of the frequency range to properly judge good tonality.

Getting back to the actual topic, I tried to use a wide variety of things. There are also other sources on the 'net that are reasonably good. One example of this would be the following recording:

From actual experience being around EMD locomotives (not working on them of course, but due to working next to a rail yard), the audio is surprisingly accurate, albeit the sound from the engine is at least 30 to 40 dB less than what you would hear at that location. Being that close to one is literally deafening. You can feel it in everything around you. But, its clear some form of a quality microphone was used since it doesn't saturate and clip. Edit: I didn't use that as a reference for the headphones. Just giving an indication that some recordings can be reasonably close to reality even in stereo. That one works much better on the floor system, but its still very much "ad-hoc", but without direct access to recording equipment and live musicians (well, I did used to play the piano to some extent in school and we had a pipe organ in the chapel. The headphones are reasonably close. But only with respect to tonality without the use of binaural recording methods from listening experience), there's not too many other options if you want a direct comparison to the source that was recorded. An additional note is that since its not music, there's less opportunities for bias since we have preconceived notions given our preferences.

 

[isostasy]

This is certainly one of the stranger ways of assessing headphones and speakers that I've seen.

 

[Cars-N-Cans]

This is certainly one of the stranger ways of assessing headphones and speakers that I've seen.

It was deliberately done not so much for headphones, but because my near-field speaker setup is a binaural system that uses passive XTC (cross-talk cancellation, in this case via head shadowing). As with conventional XTC, there is inherent coloration due to the fact that there is some form of filtering in place. Here, below 1 kHz where head shadowing is effective, both ears hear both speakers. However, above that, the contralateral speaker is no longer audible. Given the speakers have separate terminals, it was easy enough to demonstrate. The woofers don't show much interaural level differences between each ear. Pretty much what one would expect due to normal head diffraction. But the response of the tweeter is noticeably attenuated. This leads to an issue that its artificially imposing my own HRTF on the speakers response, which makes it sound dull and recessed. Using music was not terribly effective due to perceptual biases of ones expectations. I couldn't get close enough to actually get a consistent pattern in the measurements to see what corrections were needed. But, with normal non-musical sounds the coloration was much easier to hear. Once I had a rough response, semi-anechoic measurements of the speakers combined with some estimates of my own HRTFs allowed me to finally pin down what the target response needed to be. There is still some residual coloration in the crossover region between the woofers and the tweeter, but this, surprisingly, is not really audible when listening to music. Its only non-musical content that has spectra within that region that it becomes apparent that there is still some slight coloration. As far as the imaging goes, if I use ambisonic or binaural content that also has conventional stereo provided (quick example with synthesized instruments and choral vocals: MIR Pro 3D Binaural "Sonic Explorations"), the imaging between the speakers and the headphones becomes essentially verbatim. This, of course, requires listening about 45 degrees off-axis with a wide dispersion pattern speaker in the direct sound field to work or diffraction again becomes an issue, and even then I had to also take semi-anechoic measurements since I have to also correct for the off-axis response of the speakers. Surprisingly, even though the null is fairly shallow at around 8 dB or so, it still works reliably, but I had to establish an RFZ to ensure the reflections did not interfere. I did take some additional measurements using a mockup head form as well as some crude measurements at each ear opening using an iMM-6, and there is at least reasonable agreement with the measurements and the respective corrections in the target response. Still, the sound shows why XTC has been pursued. It works really, really well providing immersive imaging that even exceeds headphone listening. But, its also quite sensitive, and requires substantial investment in setup to get optimal results. In the end, multi-channel will probably be more optimal for most listening setups once some form of upmixing or new format is fully adopted in the future. It's more flexible with respect to the room and listening position. XTC setups are still very much a single-user affair, and professional implementations like the BACCH system do require head tracking for conventional setups.

But, getting back to the use of unconventional means, its because that was all I had to start with. You can't get somewhere without first finding a way to actually get there...

 

[Robbo99999]

Fine and fair enough. My apologies. But you very much gave the impression of being on a "fact-checking" mission without stopping to acknowledge that you had misinterpreted what I had said from the outset. I certainly don't fault people for making mistakes. We all do it. But it helps to at least indicate on some level that there was a misunderstanding from the outset with subsequent replies. I'm sure many of us don't mind elaborating. But this is just a text forum, so there is no context beyond what can be gleaned from the characters on the screen. Normally there would be emotions and tone of voice to indicate that someone is not following during an actual conversation. Edit: And please at least try not to strawman others arguments. In regards to (can be anything like birds and other nature sounds, fountain at the park, etc.), it's clear I was just providing that as an example to help you get some idea of what I meant. Not as an absolute statement. I think most of us know that there is a need to use a wide variety of content to accurately assess tonality.

It's alright, I was just trying to understand your original post re "what you were recording" (https://www.audiosciencereview.com/...nd-the-harman-target-curve.17914/post-1383466 ) which you've clarified now, no worries.

 

[Sean Olive]

To add to Sean’s comments, I think another thing is the lack of tactile bass. On a speaker system that can be A/B’d with headphones simultaneously, the lack of tactile feedback makes it seem like the headphones have boosted bass. It’s not until each is level matched to a level low enough to take the bass out of the equation that I realize they are in fact the same. And one has to remember that the speaker is shooting for tonally neutral sound reproduction to start with. If I record sound using a decent mic array and listen to it back thru the headphones, it’s clear they are reproducing the sound tonally. This may not be so for all users, but it at least shows for most it will provide a perceptually flat response.

That was certainly a factor when we were comparing evaluations of car audio systems insitu versus a binaural room impulse response (BRIR) version reproduced through calibrated headphones. The lack of wholebody vibration in the headphone reproductions amounted to the equivalent of 3 dB less bass compared to the insitu comparisons.

We measured the wholebody vibration using various B&K sensors and tried to simulate the vibration via a shaker on the car seat, and the extra 3 dB bass was no longer needed in the headphones.

AES E-Library » The Effect of Whole-Body Vibration on Preferred Bass Equalization in Automotive Audio Systems

A set of experiments studied the effect of whole-body vibration on preferred low frequency equalization of an automotive audio system. Listeners' bass equalization preferences were measured for four different music programs reproduced through a high quality automotive audio system auditioned in...

www.aes.org

 

[Cars-N-Cans]

That was certainly a factor when we were comparing evaluations of car audio systems insitu versus a binaural room impulse response (BRIR) version reproduced through calibrated headphones. The lack of wholebody vibration in the headphone reproductions amounted to the equivalent of 3 dB less bass compared to the insitu comparisons.

We measured the wholebody vibration using various B&K sensors and tried to simulate the vibration via a shaker on the car seat, and the extra 3 dB bass was no longer needed in the headphones.

Sean, thanks for the reply. That does make sense. I did car audio for many years, and there the bass reaches extremes as we all know. This was doubly-so when sitting in a car with a competition system. I stopped before I destroyed my hearing, but it would explain my knee-jerk reaction of the headphones having too much bass without the tactile feedback at higher volumes. At lower volumes this effect is no longer really present, but the ears response also changes.