How do MRI Headphones work? (2022)

[snakeyjake]

>The only headphone tech that I was aware of or that I'd ever really considered

I guess I'm old now because this style of headphone was present on every model of passenger aircraft in the sky when I was a young adult.

[nessus42]

When I was a kid, I once brought a stethoscope with me on the airplane so that I could watch the movie for free. (Or rather listen to it.) I pulled off the heart-listening cup part of the stethoscope and inserted beverage straws into the rubber tubing. Then I put one straw into each of the two little holes in the armrest.

It worked perfectly! Until a stewardess caught me and made me stop.

[treve]

I've never heard this before! When I started flying it was just the 2 mono jacks that you still see on planes that haven't been updated (always wondered why it wasn't just a stereo jack)

Pretty surprising to hear there's air/sound tubes rigged on to every seat on a plane.

Seems like the sound tubes ended in the 70's: https://apex.aero/articles/sound-tube-surprising-history-air...

[vidarh]

The only passenger aircraft I've ever encountered this on in 39 years of flying regularly were domestic US flights up until ~2000 or so. To the point where it's still a story I tell about the ridiculous levels of penny-pinching of US airlines (United wanted $5 to rent a plastic tube to let you listen to the inflight entertainment, with no way to plug in your own).

[mlfreeman]

I remember putting my ear up to the little holes and faintly hearing the audio even without anything plugged in.

[astrodust]

Twelve channels of the weirdest and/or lamest music you'd ever heard in your life, all in a faint, tinny form that makes AM radio sound audiophile quality.

[msisk6]

Yeah, on one armrest you had the sound-tube headphone "jack" and the other armrest had an ash tray. Wild times.

[throwaway2037]

Does anyone know why old aeroplanes used the plastic tube style of headphones, instead of copper wired? From the blog post, it makes very good sense why the MRI headphones are necessary in that setting.

Edit:

From this URL: https://avidproducts.com/2023/12/08/celebrating-70-years-of-...

This type of headphones are called pneumatic headphones.

[typhonic]

I'm thinking I'm old too because I grew up with telephones that had crystal earphones connected with non-magnetic copper wire.

[Vitaly_C]

Yes— there was a time where the free headphones were this style and you could bring your own electrically conductive headphones (with the right adapter, since it had separate RTS jacks for left and right channels) to enjoy a slightly better and louder sound quality

[jmspring]

This is certainly one of those things that has changed. I remember them too. A different era in flying.

[dusted]

I recall those being the standard for publci headphones everywhere, on planes, busses and hospitals

[agumonkey]

Hmm I can't recall my earliest flights (late 80s) but rapidly we had normal audio jacks

[FriedPickles]

I was intrigued to see a lady at the crosswalk the other day wearing earbuds with thick tubing instead of wires. Googling it, I discovered they were "EMF free headphones". Apparently enough people think electromagnetic radiation in the ears is a problem that there are now dozens of these headphones on the market that put the driver half way along the cord, with tubes proceeding to the earpiece.

[Aurornis]

> Apparently enough people think electromagnetic radiation in the ears is a problem

Even Andrew Huberman, one of the most popular health science podcasters, has dabbled into anti-EMF quackery. On one podcast he claimed that his Bluetooth headphones produced notable "heat effects", implying that the electromagnetic energy was enough to produce palpable heat in his body.

It's obviously placebo effect to the extreme (physically impossible given the amount of RF energy) but nevertheless he made the claim. Millions of people listen to that podcast.

Of course, people are catching on that Andrew Huberman isn't really a good source of scientific information (nor really a good person, given recent revelations) but the damage is done.

[vmfunction]

Well, non-ionizing radiation (NIR) cause cancer has being debated such as this [1]. It wouldn't surprise me that it will be a bit like the Roundup/Monsanto situation. I don't blame people wanting to use these kind of protection just in case.

And iPhone also had this in their Product Information Guide:

"When using iPhone near your body for voice calls or for wireless data transmission over a cellular network, keep iPhone at least 15 mm (5/8 inch) away from the body, and only use carrying cases , belt clips, or holders that do not have metal parts and that maintain at least 15 mm (5/8″) separation between iPhone and the body."

1. https://www.sciencedirect.com/science/article/abs/pii/S02697...

[gumby]

To be fair, EMF is 1/r^2 so the transducers (speakers) are indeed far from the ear. Not that they need to be, but...

[edward28]

It would be a real shame if EMF could propagate.

[Terr_]

Despite the questionable goals of the consumer, I have to credit hollow-tube technology as at least a reasonably non-fraudulent attempt to satisfy them.

In contrast, consider the glut of products involving magic nonsense about hematite beads or whatever.

[jollyllama]

They're also more durable; i.e. resistant to running over the tube portion with a chair.

[cuonic]

They also use a similar mechanism for the "get me out of here ASAP" panic button [0] that staff place in your hand and tell you to squeeze if required, all it does is detect a change in air pressure on the other end of the tubing.

[0] https://www.mriequip.com/store/pc/MRI-Non-Magnetic-Magnalarm...

[DennisP]

My house came with a button like that for the garbage disposal. Previous owner didn't like the idea of using an electrical switch with wet hands.

[focusedone]

This guy also has a post about the hierarchy of socks and underwear which resonated with me.

https://tomlingham.com/articles/an-unfortunate-hierarchy-of-...

[roughly]

There's a sci-fi book I read a while back that had as a plot point an alien species that had algorithmically optimized its decision-making processes so much that it was no longer recognizably conscious. I think about that now and again when I get a little too invested in some system or practice.

[thisgoesnowhere]

Interesting how different people's minds are.

I find the exact opposite problem, I go with old faithful over new.

It's for this reason that when I put my clothes away I simply take the stack of clothes in my dresser out, put all the fresh stuff on the bottom, then put the clothes that were in the drawer stuff on top.

I always grab the top sweater, t-shirt socks etc and I don't think about it at all.

[lynx23]

Haha, funny. It was just yesterday that I listened to a german kabarett recording which featured the fact that women are driving consumerism. And he used the exact same example: "When does he buy new clothes? When you tell him to! He would keep his current set for a lot longer." (translated from memory)

Your linked article confirms the semi-humorous statement just a day later.

[jjice]

Ha this is great! I completely relate.

There was a YouTuber (WhiteBoy7thSt if anyone is familiar) I watched over ten years ago now that came from very humble beginnings, and when he started to make real money, his first splurge (and one he stuck with) was new socks. When I say new socks, I mean new socks most days, maybe even a new pair for every day of the year. These were normal white socks, not any nice wool socks, so it was still fairly cheap, but when he grew up, they always had beaten, old socks.

[throwaway2037]

God, this blog post is hysterical. It reads like a David Foster Wallace treatment! Next time he posts something good, please -- someone -- submit on HN!

[m463]

It is wonderful and terrible to get clothing as gifts.

it seems 99% of gift clothing has some sort of special care requirements.

[layer8]

That’s why I always buy a “full” rotation. :)

[koliber]

Completely tangential story. A few months back I was getting an MRI. I stashed my belt, coins, keys, and phone. The machine started its clicking and thumping when I realized I had my wedding band on my ring finger. Immediately my mind raced to a video I once saw of an MRI machine propelling a fire extinguisher across the room. I braced for my finger to be torn off while I slowly took the wedding band off using only one hand. Luckily it stayed put through the whole scan and nothing happened.

[randlet]

If it was ferromagnetic you would likely feel it tugging as you got close to the magnet. Gold, silver, titanium are ok in MRI. However, next time, the second you realize you have metal on your person you should immediately inform the techs rather than try to just hold onto it! Aside from the risk of injury, it can be a real pain to get stuck items off the machine.

[phone[phone]]

I work on software for MRI machines, and one of the first things they do is high powered magnet safety training which is mandatory for everybody.

Even non-ferromagnetic materials react to the high field strength, and to show that, they let me hold a ring of aluminum just outside the bore. You can feel it "snap" to either parallel or perpendicular to the table when you try to turn it. It was a surreal experience.

[dessimus]

I forgot to take my tungsten carbide wedding band off as well for an MRI, nor did the MRI techs say anything. It was in the middle of the MRI scan that I realized it was still on and then my fingers on the ring hand kind of started to feel fairly warm, but not certain it that was actually the ring picking up magnetic energy or if it was psychosomatic, but no harm became of it.

I looked it up afterwards and tungsten apparently as little to no magnetic effects, but depending on the amount of carbon used in it, it can.

[itishappy]

Fun fact: metal being ripped away isn't the only negative effect possible, it can also heat up and burn you! (Why did I think this was fun again?)

https://www.sciencedirect.com/science/article/pii/S193004331...

https://www.washingtonpost.com/wellness/2023/07/26/mri-yoga-...

[typhonic]

I got my third MRI after having a titanium plate put in my neck, and wow was I more nervous that time than the earlier two times. I made the tech let me test the panic button to prove it worked. Of course there was no problem with the MRI.

[sp332]

I asked about mine, and they said it was fine for the 1.5-tesla machine but they probably would have had me remove it for the 3-tesla one. I did feel it pulsing, but not noticebly warmer.

[fluidcruft]

One of my favorite ISMRM posters that I saw in Toronto years ago was titled something like "a low-cost MRI-compatible communication system". It was really well written and you had to look at the photos to fully realize it was actually two Dixie cups connected by a string.

[throwaway2037]

Man, you really nerd sniped me here. First: ISMRM means "International Society for Magnetic Resonance in Medicine" from here: https://www.ismrm.org/

I found a bunch of posters here, but I could not find the exact one that you mentioned:

https://www.ismrm.org/19/program_files/DP02.htm

Maybe lost now? Or a different page?

[DavidVoid]

High-end headphone brand Audeze recently made an electrostatic headphone that works in MRI machines.[1] No air tubes needed and much better sound quality (and much more expensive).

[1]: https://www.audeze.com/blogs/audeze-journal/press-release-fo...

[m463]

> [Audeze has since made an audiophile version, called the CRBN headphone, read that story here.]

Very vague explanation of how they work, and that link in the middle - I suspect that is the entire point of the press release.

[timvdalen]

I made the mistake of brining an episode of 99% Invisible to an MRI. The sound quality is so bad that you barely can't make out voices. It was excruciating to listen to something I could almost understand for that time.

[djhope99]

I thought these were a nice idea when I had my MRI the other day, little did I know that I would barely be able to hear anything over the noise of the MRI machine. Ear plugs were better, kept out the noise of the MRI machine and let me drift into a trance.

[caseyohara]

I recently got an MRI and the technician asked me what I wanted to listen to on the headphones. I said "Something relaxing, do you have ambient music?". This turned out to be a terrible choice; the music was so quiet I could barely hear it. Earplugs would have been better. I had some in my pocket that I brought but it was too late.

So after the claustrophobic panic subsided and I realized I was left in there with nothing but the loud machine and my own thoughts, I decided to listen to the machine as if it were music.

I found it supremely hypnotic and trance-inducing, almost meditative. I'm a big fan of deep and hypnotic techno, so the rhythmic MRI sounds were right up my alley. I'd probably have enjoyed it more with earplugs though.

[dylan604]

What was your experience with the MRI like? Specifically, did you "feel" it? I've had my knee scanned for ACL damage, and have spoken to a few other acquaintances that have had scans as well. We've all discussed having some sensation in the exact part of the body being scanned. We all just happened to similar sports based knee injuries. It was just the slightest of tingling, but noticeable. Definitely not painful or anything scary. Was it just psychosomatic? Very possibly, but it's interesting that we all experienced it.

[Traubenfuchs]

Ok, interesting, makes sense. Next, explain to me why the MRI machine does not... take itself apart? In an MRI machine without a cover you can see all kinds of micro and macro machinery, cables, fans, plating, sensors, magnetrons, pulse transformators, gun drivers... Pretty much each of those parts would be pulled through the room and get stuck to the MRI machine if brought in individually, or am I wrong?

https://www.google.com/search?q=mri+without+cover&tbm=isch

[r2_pilot]

The engineers have accounted for this and appropriately fasten the individual components to the machine rather than bringing the parts in for assembling the machine while the high powered magnetic field is present.

[birdman3131]

I must be from a different era because a cup and string was well known as a kid as a way of transmitting sound. This is a very similar process.

[lynx23]

Ahh, memories. Roughly 20 years ago, I took part in a research experiment which had as its aim to figure out which brain areas were involved when a blind person reads Braille. TL;DR: They had a hypothesis, which was mostly confirmed. It happens in the visual cortex. Anyways, back then, MRI was still newish tech. FMRI wasnt used much in typical medical settings, but for research. As part of the deal, the MRI technicians did share a lot of gossip and random knowledge during the rather long preparation times. Long story short, this is when I learnt about the tubed earphones. And all the other mechanisms which were constructed to transport the braille strip wthout operating a real motor inside the magnetic field... Was almost worth the 4 hours of having to absolutely lie still...

[slowtokyo]

So how do the microphones that you use to talk to the tech in the MRI machine work?

[jagged-chisel]

> I'm not allowed to have any metals or magnetic materials on me.

Loose or easily dislodged materials. My belt buckle was ok to keep on. Had to empty my pockets, take off my ring, metal piercings are disallowed.

You don’t want gobs of belongings piling up on your magnet, and you don’t want something large enough to pin the human between it and the magnet. The first scenario is quite expensive to rectify. The second is quite expensive, quite painful, probably fatal, and certainly traumatic.

[roywiggins]

Also important: no fabrics with metal fibers.

https://www.ajnr.org/content/34/5/E47.full

[bpye]

Does this possibly depend on the field strength? I was asked to change into a hospital gown when I had an MRI a couple years ago.

[jlarocco]

These are popular with two-way radios, where they're called acoustic tube earbuds.

I'd guess the tube is longer in an MRI, though.

[rjmunro]

TV presenters often use them; presumably the clear plastic tube are supposed to be harder to see.

[anfractuosity]

Interesting, sound kind of like a stethoscope.

I bought a kind of unusual type of headphone from aliexpress a little while ago, that essentially consists of an induction loop you wear round your neck and tiny magnets you put in your ear, I'm somewhat scared to try them out as I don't especially want them to get stuck in my ear.

[aitchnyu]

Tangential, I saw an episode of House where he put a patient with medical implants into an MRI and they ran it for a few seconds till the burning was too painful. Was this realistic?

[lostlogin]

It happens sometimes. I’ve been there for it with an infected filling (patient was unaware - they went to a dentist and reported back), with tattooed eyebrows and anyone with a cochlear implant tends to suffer (from the torque, not heating).

There is the odd burn - rare, and mostly preventable. Burns are the most common class or MRI injury.

I’m an MR tech.

[tsol]

I remember there was an episode where this happens with a prison tattoo-- some of them can contain heavy metals that react in an MRI.

[denton-scratch]

I haven't flown for many years; but I think I remember airline headphones that were connected to the seat-handle with a hollow plastic tube.

They were awful.

[fortran77]

This is exactly how headphones on passenger airlines worked several decades ago, until about 1990.

[amelius]

So they work like a stethoscope.

Would they sound better if they used a liquid instead of air for the conduction?

[noobermin]

Probably not, recall how sounds sound underwater, they do not sound like they do above it.

[EnzymeFestival]

What options exist for something superior? These headphones are awful

[Retr0id]

MEMS https://usound.com/usound-introduces-patient-safe-mems-louds...

Datasheet (PDF) https://usound.com/download/achelous-datasheet/?wpdmdl=746

[ricardobeat]

Electrostatic headphones: https://www.audeze.com/blogs/audeze-journal/press-release-fo...

[roywiggins]

You can technically alter the sequence to make the scanner itself produce music. I don't know if anyone actually does this...

https://pubmed.ncbi.nlm.nih.gov/26178439/

[astrodust]

Stimulating the audio processing part of your brain directly with the MRI machine.

[lakpan]

Hire a non-metal band to play for you in the room.

[riffic]

tldr it's a pneumatic tube like a stethoscope. these used to be used within aircraft as well for inflight entertainment.

[doctorhandshake]

I used to love trying to surreptitiously unplug my traveling companions’ headphones so I could blow into the end of the tube. Never once pulled it off.

[lxgr]

I've been on an airplane that used these! I think it even had a channel selector near the plug if I remember correctly (it's been a while).

[myfonj]

> The sound is transported along the tube via air — a very simple solution. Though this also explains why they sound absolutely terrible.

I see it is simple, but I wonder, would it be possible to use different sound medium ("conductor")? Some liquid, water perhaps? Would elasticity of the tube eat more signal than is lost in the air? Too heavy? Leaky? Questions…