Eardrum Suck: The Mystery Solved (2019) | Hacker News Reader

Eardrum Suck: The Mystery Solved (2019)

soundstagesolo.com

58 pointsTomte15 comments

Someone at work once explained the origin to me (and my employer has done work for more than one of the manufacturers of noise cancelling headphones). The cause, as identified in the article, is when expected low frequency sound components are missing.

The normal "real world" way you selectively lose low frequencies is when there is a pressure differential across the eardrum - this stretches it and prevents it vibrating in the same way, losing the lower frequencies first. So the brain associates that experience with low pressure and gives the right sensation.

In my opinion, you're spot on: being deprived of hearing the lowest frequencies typically occurs only when there's a pressure imbalance between the inner and outer ear. Therefore, when you experience silence at these lowest frequencies due to noise cancelling, your brain may assume a pressure imbalance must be the cause.

I've had the opportunity to use a variety of noise cancelling headphones over the years, from various brands, both in-ear and over-ear, and they all had this effect.

The good news is that you can become completely accustomed to it: after a while, the brain understands that there's no pressure imbalance, and it becomes a non-issue. Not hearing low frequencies is exactly what we expect from the product.

The article goes further to discuss some slope in a graph around 500Hz, which might be true, but I don't subscribe to that. It seems unnecessary to explain the observed facts and adds nothing.

What is not addressed at all is why all models seem to emit a subtle continuous shhhhhhh across a broad range of high frequencies. It's so subtle that you can only notice it when the outside environment is already quiet. I've never been certain whether it's just noise from the signal processing. My intuition is that it's artificially added to prevent inducing tinnitus in some users.

I experience this, and find noise cancelling headphones painful to wear. My assumption had always been that the antiphase somehow created a * hand-wavy * “DC offset” in eardrum pressure.

But if this article is correct, the pain is perceptive rather than physical. Given how complicated perception is, it won’t surprise me. Maybe there’s a mind trick to stop experiencing the pain.

speaking to myself:

the pain is real, but caused by muscle contraction/cramp as a reaction to a sensation. You've taught yourself to wince until it hurts, and now contribute the pain to external factors. You've come to expect the pain, so it'll hurt.

The mind trick is right there: understand that you cause the pain yourself as reaction to a sensation and be mindful in situations where it might happen. You will find that the pain is caused from expectation and habit, this knowledge will break the cycle. Keep it up a for a few months and you'll untrain your habit a great deal.

this seems to be the same psychoacoustic effect as after some sudden tinnitus onset with partial hearing loss. the loss of certain high frequencies acts like the successful wave cancellation, the high tinnitus replacing certain frequencies acts like the feedback squealing. it also feels like in an airplane or elevator. if low frequencies are affected, the relative to common experience too loud high frequencies feel like hissing. both are extremely unpleasant.

> Until recently, the models most notorious for eardrum suck have been Bose over-ear noise-canceling headphones, such as the QC25s and QC35 IIs. Yet as anyone who’s taken a commercial airline flight in the last decade can attest, these models are immensely popular. Clearly, some people either don’t experience eardrum suck, or do experience it but aren’t bothered by it.

I can explain that. Bose doesn't sell regular headphones. Noise-canceling headphones are the only option. So you use "noise-canceling headphones", but you don't turn on the noise canceling because of the uncomfortable pressure on your ears.

> People sometimes report the same effect when they go into anechoic chambers.

That was my immediate though about this. When you go into an anechoic chamber, the loss of ambient sound makes you feel like you've gone deaf, which is as if something was stuffed into your ear.

I think your ear basically uses the change in ambient sound as a cue which produces the stuffy feeling.

A bakery in a supermarket entrance area nearby has some tables at a wall. They put thick upholstery on the wall. Sitting there has a similar effect, especially when the area is busy because the sound reflections from that wall are "missing".

> More advanced noise-canceling headphones, such as the Bose QC35 IIs and Sony WH-1000XM3s, add feed-forward noise-canceling, which uses a microphone (or two) on the outer shell of the headphones to pick up the environmental noise.

My oooold Bose QC15s already have microphones on the outer shell - not sure what they are used for, but they are definitely there, with a quite prominent grille...

Noise cancelling headphones need to listen to ambient sound to cancel out the sound, plus you can use them in voice chat.

3M highest level protection earmuffs are great. Electronic noise cancellation is a silly gimmick IMO.

Perhaps a stupid question, as I've never experienced this, but it sounds like the effect is most pronounced when noise cancelling is first engaged. Could you simply enable noise cancelling before putting on the headphones? And then perhaps place them onto your ears slowly?

No, the effect is caused by the noise canceling being active, not by the noise canceling becoming active. It doesn't get more or less pronounced over time.

Interesting... I experience this effect to the point where I almost never use the noise-cancelling function for headphones, instead I prefer passive noise insulation. Someday I'd love to have custom IEMs.

So just add a little bit of noise back to the signal (this can be noise that sounds better than the original noise). Pink noise perhaps.

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