Noise Reduction and Headphones

[ahofer]

I'm following Amir's decision to do headphone reviews closely. I'm not a big headphone user, partly for fear of hearing loss, but I have a pair of HD 650 (see listening note below) that I use occasionally.

I also have some Bose noise cancelling IEM for my phone, that I sometimes use on my PC or through a DAC. One thing I notice when I plug these into a DAC is that I turn the volume down quite a bit when noise cancelling is on, and I can still hear a ton of detail. Given the hearing loss danger of extended headphone listening, it seems that noise cancellation could be a really important feature.

Does noise cancellation interfere with fidelity? Obviously, it can't be implemented in open-ear designs, but are there other reasons it shouldn't be used in high end designs?

Listening note on HD650: With an iFi iDSD Pro DAC they sound veiled. With my RME DAC they sound much clearer. I'm assuming this is some sort of impedance/power effect, but it's quite pronounced. The Bose sound OK, but have an exaggerated bottom, probably by design.

 

[pozz]

Does noise cancellation interfere with fidelity? Obviously, it can't be implemented in open-ear designs, but are there other reasons it shouldn't be used in high end designs?

No, I've found ANC devices to be excellent. Their only real drawback is that the ANC is so much better in quality than the basic quality of the headphone or earphone. Boatloads of money have been poored into getting ANC right in both reception and playback, since it sells well, but not optimal sound quality, paradoxically.

I also think there is no real reason that ANC can't be used with open-backed designs, since it's typicaly based on parametric arrays that sense direction as well as level. A well-designed system should be able to cancel background noise but keep the response directed at the ear unchanged.

 

[solderdude]

Does noise cancellation interfere with fidelity? Obviously, it can't be implemented in open-ear designs, but are there other reasons it shouldn't be used in high end designs?

Noise Cancellation lowers distortion in the lowest frequencies < 400Hz but above it there can be negative effects. It does not work for frequencies > 500Hz or so.
Noise cancelling basically is a feedback loop (frequency limited) by a microphone in front or next to the driver. The signal from the mic is compared to the input signal so differences (sounds coming from the outside) are present in counterphase and thus cancel.
This can never be 'perfect' and is quite limited in capabilities.
An example is seen here and here where for lower freq. the distortion improves but for the mids it gets worse.
WH1000XM3:

Modern NC headphones also have mic arrays that can be used to make phone calls and so you can 'mix' outside noises in the signal path so you can hear people around you.

It basically is very similar to the MFB speakers. These too were bandwidth limited.

 

[Vincent Kars]

Given the hearing loss danger of extended headphone listening

What make you think so?

Hearing loss has nothing to do with headphones.
Long exposure to loud noise will damage your hearing in the long run.

 

[M00ndancer]

One thing I notice when I plug these into a DAC is that I turn the volume down quite a bit when noise cancelling is on, and I can still hear a ton of detail.

Noise Cancellation lowers distortion in the lowest frequencies < 400Hz but above it there can be negative effects. It does not work for frequencies > 500Hz or so.

The benefit from ANC headphones like in-ears you have and my over-ears is exactly like @solderdude states. The rest of the NC is physical.
In your case a good seal between the ear canal and the in-ears. In my case, a closed back headphone with good sound isolation.

The problem with open back is the fact that they are open. You hear the surrounding noices, raise the volume to compensate for that. Just like me in the 80-ies using my Sony Walkman on the subway. Apple airpods suffer from the same problem. Thus giving me a non age reduction in the 8k part of the spectrum. Together with age. What I did to cure much of high volume usage was to start listening to everything at very low level , retraining my ears. Now I listen at around 50% less volume than before, saving my hearing.

The only thing that can save your hearing is lower volume.

 

[ahofer]

What make you think so?

Hearing loss has nothing to do with headphones.
Long exposure to loud noise will damage your hearing in the long run.

Hearing loss appears to be correlated with heavy headphone use. Granted, it is your choice of listening level that counts, but have a look at the extended dialogue on SPL levels in the Sennheiser review thread. It is my contention that using earphones a lot increases the risk/likeliness of greater exposure to louder SPLs, particularly peak. Some of that is how one behaves/reacts with the volume control - hence the NC question, as when I turn it on, even in a quiet setting, I turn the volume down and get equally satisfying results.

https://sites.kowsarpub.com/healthscope/articles/65901.html
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5501022/

https://www.audiosciencereview.com/...00s-review-headphone.18424/page-3#post-601432

My mind's open, but I don't think you can say it "has nothing to do" with headphones.

 

[Willem]

I guess it is the lack of a reference sound level from the surrounding noise that prevents you from assessing how loud you are really playing with your headphones. So do headphones make you deaf? Yes and no. In Europe, there are mandatory sound level limits for headphone use.

 

[ahofer]

I guess it is the lack of a reference sound level from the surrounding noise that prevents you from assessing how loud you are really playing with your headphones. So do headphones make you deaf? Yes and no. In Europe, there are mandatory sound level limits for headphone use.

And I've noticed a variety of limitation options in software - iPhones, Roon, etc. There certainly seems to be a behavioral connection to raising volume in headphones, much like the theory behind why foods with high glycemic index are associated with weight gain - they aren't worse *per calorie* necessarily, but they leave you hungry after provoking an insulin spike (that's the theory, I'm not qualified to assess it).