ANC Is More Complicated Than It Sounds: Advanced ANC Headphone Measurements
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ejacobsen

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Important thoughts here. Thank you for this.
My simple take away: loudness-sensitivity-weighted ANC and masking-effect-aware ANC will lead to ANC performance that real listeners prefer.
That's good news for us!
 
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Mr.Jacob

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More seriously, I'm wondering if there are known ANC approaches focused on noise shaping(so obviously leading to a louder overall noise), instead of just trying to attenuate everything as much as possible? Or maybe given the tiny distance between the mics and output drivers, we just cannot afford lag from computational work? but that should be easier to handle nowadays I imagine.
One specific noise I'm thinking of would be some rather consistent modulations within the noise like say we have mainly a 80Hz hum, but it fluctuates in amplitude with say a 0.5s second periodicity(or similar stuff we often find in public transportation). That's more annoying than just a stable 80Hz hum and some form of noise shaping target could probably do well in mitigating such sounds by reducing the amplitude of that specific periodicity. and that without having to need complex processes trying to identify it. Seems like I'm talking to myself but information or even educated guesses are welcome.
That's an interesting idea, because of the ability to essentially favor certain frequencies over others, but implementing this in an ANC design would definitely require some creative solutions. The ANC headphone will typically use some combination of passive attenuation and then feedback/forward circuits to create the mirror image sound to cancel the acoustic sound. So any noise shaping techniques would be applied to the "mirror sound" only. Of course FB/FF ANC systems operate optimally at different frequencies, which is where designers can play some games regarding what mirror sounds are created, and ultimately what residual sound is left at the ears.
I can't possibly answer the question if some companies are doing this for ANC, but my hope/goal is that the companies focus more on the sounds and patterns that the human ears are more sensitive to.

IMO, using the metrics mentioned in the video (and of course there are more metrics like them out there to be considered too) is a great way to indicate whether your ANC implementation has been effective.

And your 80Hz pulsating noise example is spot on about something that is subjectively very annoying. The human ear is indeed particularly sensitive to distinct repetitious patterns in sound.
 
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kyotousa

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Most on head-fi are aware about what I'm about to say, but In case anyone reads this and is not 100% clear - noise-cancelling buds/headphones provide little if any protection from hearing loss. They just make it easier to listen to music at lower volume level being they reduce background noise. Noise-cancelling devices no substitute for properly fitted earplugs w/ excellent noise protection rating. We provided earplugs with 32dB noise reduction for all employees. Being one who spent many years attending arena concerts w/o hearing protection, became advocate for hearing protection. If my message spares anyone from further damage to their hearing, I'll have done my job. Head-fi readers are pretty educated about excessive music playback volume, but in case anyone reading this is unclear: Noise-cancelling devices do not protect you from hearing loss, they enable you to listen at lower volume, as they cancel-out some background noise. Whether one uses noise-cancelling devices to help listen to music more safely at lower volume, or continues to listen at higher volumes is their choice. Make the right choice and maybe retain decent hearing for much of your life.
Isn't what you wrote contradictory to itself. You said, it's not 100% clear that noise cancelling headphone provide protection from hearing loss.
Yet you also said it makes listen to music at lower volume level (which obviously should protect hearing loss).
It protects yourself from raising up the volume of music to > ambient noise, no?

Obviously, if the ambient noise is so great that it would damage hearing then what you wrote is plausible.

The people over at Audio Science Review could really learn few things from this guy. Great to see someone actually doing scientific work to explain what humans perceive, rather that just blindly trusting whatever measurement standard they have, and disregarding anything not showing up on it, as lies and delusions of filthy humans...
Do you not know ASR has subjective hearing test as well? I think the point is to pass both subjective and objective tests.
I mean if you can't pass a basic objective tests, then how could it perform well?

The logic is that test might be flawed that if the instrument fooled the test and still sound terrible, but not other way around.
 
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sidecross

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The arguments here seem to be like the one science had about light being a wave or particle.

For me listening to music depends on room or environment and ambient sound there upon.

ANC works for moderate ambient noise levels, but for mass transit and like high ambient noise levels at that level it does not work for me. For those who need to listen to Bach on a roller coaster I hope you find what you need. :)
 
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Do you not know ASR has subjective hearing test as well? I think the point is to pass both subjective and objective tests.
I mean if you can't pass a basic objective tests, then how could it perform well?

The logic is that test might be flawed that if the instrument fooled the test and still sound terrible, but not other way around.
I don’t entirely doubt the intentions of the founders - the problem is the site has become a hive for people who will onsite, and on other forums, adamantly claim that fx. All DACs sound the exact same, because they measure similarly within the limited scope of measurements they do.
And will ridicule anyone who claims to hear any differences.
That’s borderline like like measuring a fruits height and width, and claiming all fruits that are roughly the same height and width, therefore must taste the same - in that it’s a ridiculously flawed approach to assume you can measure all there is to know about fruits with just a ruler.
 
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I don’t entirely doubt the intentions of the founders - the problem is the site has become a hive for people who will onsite, and on other forums, adamantly claim that fx. All DACs sound the exact same, because they measure similarly within the limited scope of measurements they do.
And will ridicule anyone who claims to hear any differences.
That’s borderline like like measuring a fruits height and width, and claiming all fruits that are roughly the same height and width, therefore must taste the same - in that it’s a ridiculously flawed approach to assume you can measure all there is to know about fruits with just a ruler.
The problem of the discussion is a gross amount of certainty in any one position of view point.

Science should have reminded us of certain principles that were argued before a level of acceptance, to name a few 'Uncertainty Principle', 'Special Relativity Theory, or 'Wave Particle Duality of Light Theory'.

'The larger the bonfire the more darkness is revealed' Dennis McKenna
 
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I don’t entirely doubt the intentions of the founders - the problem is the site has become a hive for people who will onsite, and on other forums, adamantly claim that fx. All DACs sound the exact same, because they measure similarly within the limited scope of measurements they do.
And will ridicule anyone who claims to hear any differences.
That’s borderline like like measuring a fruits height and width, and claiming all fruits that are roughly the same height and width, therefore must taste the same - in that it’s a ridiculously flawed approach to assume you can measure all there is to know about fruits with just a ruler.
I'm pretty sure it's because the measurement is not a continuous measurement, so it's flawed hence there's also a subjective listening test.
Besides what's the point to discredit the integrity of the site based on some users who didn't take the time to understand it. I personally thinks it's a great site and the founder has the background to back it up.

A lot of the DAC/Amp "feel" is indeed just subjective anyway.
 
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I'm pretty sure it's because the measurement is not a continuous measurement, so it's flawed hence there's also a subjective listening test.
Besides what's the point to discredit the integrity of the site based on some users who didn't take the time to understand it. I personally thinks it's a great site and the founder has the background to back it up.

A lot of the DAC/Amp "feel" is indeed just subjective anyway.
The point is it is literally all I see there, and I see this “anti-science, claiming to be science”-behavior and mentality seep into other sites as well - it’s a cancerous behavior, and it’s spreading.
it’s ruining it for people looking for actual useful advice, other than “it doesn’t matter, they all sound the same, so just buy the cheapest one with the features you want”, putting them off the hobby, similar to the old-school audiophiles I’ve run into who claim Vinyl is the ‘best’ format in the face of all facts. Both about equally flawed and anti-knowledge.

And I hardly qualify a single sentence saying “I listened to it with my HD600, and it sounded fine.” A listening test.

Well, I suppose it’s a listening test in the same sense that their measurements are: it’ll tell you if the unit is straight up broken or badly made, but won’t actually tell you much useful information beyond that.

I don’t know the background of the founder, considering the Incomplete methodology and measurements, and conclusions being based on them, I hope he’s not working with anything remotely similar professionally - or at least takes a different approach.

Well, enough of that - it’s not what this thread is about :)
 
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sidecross

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"... it’s ruining it for people looking for actual useful advice, other than “it doesn’t matter, they all sound the same, so just buy the cheapest one with the features you want”, putting them off the hobby, similar to the old-school audiophiles I’ve run into who claim Vinyl is the ‘best’ format in the face of all facts. Both about equally flawed and anti-knowledge..."

I come here for information and not advise, and how that information is provided and its context is what I judge when I post a comment.
 
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Well, enough of that - it’s not what this thread is about
Mmaybe you could have considered that on your very first post in the thread instead of deciding to settle a personal score out of nowhere. Better late than never, I guess ^_^.


@Mr.Jacob. How much do I mess with your ranking system once I start applying my favorite EQ to the ANC headphone? Because I will. Oh yes I will!
It's a trick question, now you have to explain how to "volume" match 2 headphones with different frequency responses.:smiling_imp:
 
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kyotousa

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The point is it is literally all I see there, and I see this “anti-science, claiming to be science”-behavior and mentality seep into other sites as well - it’s a cancerous behavior, and it’s spreading.
it’s ruining it for people looking for actual useful advice, other than “it doesn’t matter, they all sound the same, so just buy the cheapest one with the features you want”, putting them off the hobby, similar to the old-school audiophiles I’ve run into who claim Vinyl is the ‘best’ format in the face of all facts. Both about equally flawed and anti-knowledge.

And I hardly qualify a single sentence saying “I listened to it with my HD600, and it sounded fine.” A listening test.

Well, I suppose it’s a listening test in the same sense that their measurements are: it’ll tell you if the unit is straight up broken or badly made, but won’t actually tell you much useful information beyond that.

I don’t know the background of the founder, considering the Incomplete methodology and measurements, and conclusions being based on them, I hope he’s not working with anything remotely similar professionally - or at least takes a different approach.

Well, enough of that - it’s not what this thread is about :)
Well, what you just wrote is completely different from the ASR site. It seems like you never visited the site and just make false claim about it.
So I agree, there's no point discussing ASR if you have absolutely no idea about it.
 
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Mr.Jacob

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@Mr.Jacob. How much do I mess with your ranking system once I start applying my favorite EQ to the ANC headphone? Because I will. Oh yes I will!
It's a trick question, now you have to explain how to "volume" match 2 headphones with different frequency responses.:smiling_imp:
Oh man. I sense trouble.

Firstly, regarding the ANC study, the only place where we really factored in the output of the headphones, was for the final 3QUEST analysis. (all the other tests were with no headphone playback, just different ANC modes and varying BGN scenarios) For the 3QUEST tests we wanted to check the speech quality reproduction in the presence of noise. And the volume matching we did on those headphones was to gauge - and set - overall Active Speech Level (acc. to ITU-T P.56) when no noise is present. I *think* we used a 16sec speech file (4x4sec segments of speech with pauses). That gives us realistic source material with fairly broadband stimulation, and gets us close enough to volume matching the headphone outputs for THIS study.

Secondly (and more importantly?), how would I volume match headphones for frequency response comparisons? Traditionally, and from a standards perspective, frequency response is defined as output/input. When you measure the headphone (or other audio device) that way, it gives you the 'transfer function' of the system and makes the resulting plot independent from your input (as long as you are away from the rails). Therefore you can compare curves directly.
Of course, that often means the two curves don't necessarily overlap or line up neatly, which is why people resort to plotting headphone response versus dB SPL and pinning the headphone responses at a certain frequency and output (500Hz/1kHz @ 94/90dB SPL whatever.). However, if volume matching is done so we can easily compare frequency responses to make a judgement call on which headphone might be better(?) - or to set levels prior to subjective listening - then your choice of frequency can be hugely important.

I think @arnaud alluded to a conversation he had with @jude earlier in this thread about using Loudness for this, which sounds like a good approach. Along the same lines as this discussion thread about ANC, a lot of the same psycoacoustic principles could be applied here:
(1) If you are using a broadband and time-varying source material (speech/music) to stimulate your headphones, you are arguably placing them in a realistic mode of operation (unlike pure tones).
(2) If you are analyzing the resulting output using an advanced hearing model based loudness metric, you can then adjust the volumes so they match on a scale of subjective magnitude. Again, that should get you as close to doing this by ear.
(3) When you then run the frequency response measurements, you should be able to better see the balance of each headphone as well as where they differ.
(4) When you subjectively listen to the headphones, you should be perceiving them as close to the same amplitude - remove that variable in your evaluation - and focus on other elements in the audio playback.

It's honestly not something I have spent a lot of time investigating, but it seems like it has potential.
 
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Oh man. I sense trouble.

Firstly, regarding the ANC study, the only place where we really factored in the output of the headphones, was for the final 3QUEST analysis. (all the other tests were with no headphone playback, just different ANC modes and varying BGN scenarios) For the 3QUEST tests we wanted to check the speech quality reproduction in the presence of noise. And the volume matching we did on those headphones was to gauge - and set - overall Active Speech Level (acc. to ITU-T P.56) when no noise is present. I *think* we used a 16sec speech file (4x4sec segments of speech with pauses). That gives us realistic source material with fairly broadband stimulation, and gets us close enough to volume matching the headphone outputs for THIS study.

Secondly (and more importantly?), how would I volume match headphones for frequency response comparisons? Traditionally, and from a standards perspective, frequency response is defined as output/input. When you measure the headphone (or other audio device) that way, it gives you the 'transfer function' of the system and makes the resulting plot independent from your input (as long as you are away from the rails). Therefore you can compare curves directly.
Of course, that often means the two curves don't necessarily overlap or line up neatly, which is why people resort to plotting headphone response versus dB SPL and pinning the headphone responses at a certain frequency and output (500Hz/1kHz @ 94/90dB SPL whatever.). However, if volume matching is done so we can easily compare frequency responses to make a judgement call on which headphone might be better(?) - or to set levels prior to subjective listening - then your choice of frequency can be hugely important.

I think @arnaud alluded to a conversation he had with @jude earlier in this thread about using Loudness for this, which sounds like a good approach. Along the same lines as this discussion thread about ANC, a lot of the same psycoacoustic principles could be applied here:
(1) If you are using a broadband and time-varying source material (speech/music) to stimulate your headphones, you are arguably placing them in a realistic mode of operation (unlike pure tones).
(2) If you are analyzing the resulting output using an advanced hearing model based loudness metric, you can then adjust the volumes so they match on a scale of subjective magnitude. Again, that should get you as close to doing this by ear.
(3) When you then run the frequency response measurements, you should be able to better see the balance of each headphone as well as where they differ.
(4) When you subjectively listen to the headphones, you should be perceiving them as close to the same amplitude - remove that variable in your evaluation - and focus on other elements in the audio playback.

It's honestly not something I have spent a lot of time investigating, but it seems like it has potential.
Mr Jacob, I admire your ability as a teacher and a person with an enormous amount of patience and generosity of your time. You should be appreciated by all who visit this site for good information on audio technology. Thank you!
 
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Mr.Jacob

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Mr Jacob, I admire your ability as a teacher and a person with an enormous amount of patience and generosity of your time. You should be appreciated by all who visit this site for good information on audio technology. Thank you!
Well that brightens my day! Thanks @sidecross! :beerchug:
 
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