[HN Gopher] How do MRI Headphones work? (2022)
___________________________________________________________________
How do MRI Headphones work? (2022)
Author : kbf
Score : 80 points
Date : 2024-03-25 13:39 UTC (1 days ago)
(HTM) web link (tomlingham.com)
(TXT) w3m dump (tomlingham.com)
| riffic wrote:
| tldr it's a pneumatic tube like a stethoscope. these used to be
| used within aircraft as well for inflight entertainment.
| lxgr wrote:
| 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).
| riffic wrote:
| EDIT i'm wrong the speaker was inside the armrest.
|
| I wouldn't be surprised if the channel selector wheel was a
| simple mechanical acoustic coupler rotating to connect or cap
| upstream source tubes. I remember it as well flying in the
| late 80s or early 90s.
| denton-scratch wrote:
| > a simple mechanical acoustic coupler
|
| I get what you're saying, and I think that's plausible. But
| as far as I'm concerned, an _acoustic coupler_ is /was a
| type of modem, into which you plugged an ordinary telephone
| handset. You had to have a telephone that had hemispherical
| mike and earphone; it didn't work with e.g. a trimphone.
| Expected performance: 9,600 bits-per-second.
| riffic wrote:
| "coupling" then, whatevs.
|
| lemme see if I can dig up a patent number for the channel
| switcher wheel and put this pondering to rest.
|
| seems the inventing corporation is still around haha
|
| https://avidproducts.com/2023/12/08/celebrating-70-years-
| of-...
| throwway120385 wrote:
| Yep right next to the ashtray.
| ortusdux wrote:
| I remember being able to select the pilot coms. I was nervous
| on my first flight as a kid, and it was very calming to hear
| the preflight checklist and ATC communication in the classic
| pilot cadence. This was pre 9-11.
|
| I did wonder on my last flight if I could use SDR & android
| to listen in.
| lxgr wrote:
| You can just use LiveATC on your phone these days, since
| many flights now have gate-to-gate Wi-Fi.
|
| I think it's not allowed to actually operate a radio
| receiver on an airplane in the us:
| https://travel.stackexchange.com/questions/2322/can-i-
| listen...
|
| Some airlines might still have the "listen to ATC" feature
| available, but in my experience, it's the pilots' decision
| whether that's available or not, and I've only ever been
| able to use it on a United flight once.
|
| Sirius XM on JetBlue also has an "ATC channel", but I've
| only ever heard silence there, and I'm not sure if that's a
| similar thing (i.e. sourced locally), or just a random ATC
| feed from somewhere in the country relayed via satellite.
| doctorhandshake wrote:
| 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.
| myfonj wrote:
| > 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...
| focusedone wrote:
| 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-...
| thisgoesnowhere wrote:
| 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.
| adolph wrote:
| FILO is not the standard method of maintaining one's stock of
| clothes? How else does a person mange wear leveling?
| edward28 wrote:
| Simply pop from the bottom of the dresser.
| causi wrote:
| You shouldn't. If you successfully manage wear leveling all
| you've done is make sure you have to replace your whole
| stock at the same time, as well as depriving yourself of
| regular reminders of what new-ish clothes should look and
| feel like, leading you to keep wearing worn-out clothes.
| mnw21cam wrote:
| With socks, wear levelling is actually really useful. I
| tend to buy a whole rotation of identical black socks,
| and then I don't need to pair them up individually. Also,
| buying 15 pairs of socks in one go isn't going to break
| the bank.
| causi wrote:
| But what's the use in that "useful"? When I pick up a
| sock and it has holes, I throw it out. When the drawer
| gets empty enough it can fit another package, I buy one.
| What utility would come from worrying about when I used a
| particular sock?
| toast0 wrote:
| It can be hard to find the same model sock when you need
| to restock. Wear leveling and replacing them all at once
| eliminates difficulty with matching. Also, if you don't
| wear level, you may have one new sock and one worn sock,
| and that can be weird.
| JohnFen wrote:
| > If you successfully manage wear leveling all you've
| done is make sure you have to replace your whole stock at
| the same time
|
| I've been doing this for decades, but have never
| encountered this problem. I think because of a
| combination of the fact that I didn't buy my entire
| wardrobe all at once to begin with and that different
| clothes wear at different rates.
| cyberax wrote:
| My process:
|
| 1. Buy ~15 copies of everything.
|
| 2. Not think about what to wear! Everything is roughly the
| same.
|
| 3. Throw out everything every ~3 years. A couple of months
| before that, start buying new models of clothes to find the
| best one.
|
| 4. Goto 1.
| tonyarkles wrote:
| Lol, since we're going down this road... my clothing ends
| up getting stored more as a cache with an LRU policy. Every
| 6 months or so the items at the bottom of the drawer get
| assessed for eviction (donation). My favourite items are
| always on top, less used items are easy to find, and the
| unused items are easy to identify.
| throwway120385 wrote:
| I wear whatever makes me feel good.
| roughly wrote:
| 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.
| crashmat wrote:
| Was it good? Do you have the title?
| thescriptkiddie wrote:
| they may be referring to blindsight by peter watts
| pinko wrote:
| Probably _Blindsight_ by Peter Watts
| jjice wrote:
| 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.
| hobs wrote:
| This hits way too close to home. This was the thing I was
| going to do when I was rich, and now that I make enough money
| I barely even wear socks, lol.
| lynx23 wrote:
| 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.
| layer8 wrote:
| That's why I always buy a "full" rotation. :)
| djhope99 wrote:
| 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.
| dylan604 wrote:
| 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.
| tgv wrote:
| MRI can cause a tingling sensation. Apparently, it can be
| quite noticeable when you make a loop, e.g. with your arms.
| See peripheral nerve stimulation.
| dylan604 wrote:
| make a loop? wouldn't that require breaking the cardinal
| rule of not moving during the scan?
| green-salt wrote:
| For my knee scans I could move into a position that was
| comfortable for me which actually I think was arms folded
| across my abdomen, but then you just do not move while
| the imaging is happening, which will have a distinct
| sound.
| zrail wrote:
| I have had an abdomen MRI. I definitely felt sensations when
| the machine was doing particular sets of scans.
|
| Also, I accidentally left my wedding ring on (I informed
| them, they were not interested in the slightest). My right
| felt hot during the scans. Not painful burning hot, but
| warmer than body temp for sure.
| dylan604 wrote:
| I guess forgetting your gold ring in an MRI lets you know
| it's not gold plating of a cheaper metal!
| riahi wrote:
| The RF pulses and field gradients can directly stimulate the
| peripheral nerves. I have had involuntary muscle twitching
| triggered by many pulse sequences. It's not unheard of. It
| made me more sympathetic for patients who have motion in
| images. It could be that the particular combination of pulse
| sequence and their nerves don't jive and triggers movement.
|
| Source: Radiologist (and personal experience in the bore)
| caseyohara wrote:
| 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.
| jonah wrote:
| When I had an MRI a few years ago, my conclusion about the
| sound was "add a melody on top of that rhythm, and it would
| go over quite well in an underground industrial music club in
| an abandoned warehouse outside of Berlin."
|
| I haven't looked to see if anyone has actually tried to make
| music with the sound or not.
| mb7733 wrote:
| You're not alone. The "music" combined with the visual
| sensory deprevation can be a trip. Some machines are
| completely featureless on the inside and I've found it can
| feel like I'm floating in a bit open space, not crammed into
| a magnetic tube!
| mcbain wrote:
| I get an MRI Brain every three months. I usually opt out of
| the piped music - mostly because it's either a bad choice by
| the radiology techs or tuned to a generically awful radio
| station - but the headphones lock into the head cradle so I
| use them with earplugs underneath. I close my eyes and tune
| out and try to not sleep (and twitch so they have to restart
| the capture).
|
| Some of the pulse sequences are rhythmic and I find the
| entire thing somewhat meditative, but there are many other
| places I'd rather be.
| adrianmonk wrote:
| > _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._
|
| That was a golden opportunity to experience ambient music in
| the most historically authentic way possible!
|
| Listen to Brian Eno's story of what inspired his 1978 album,
| "Ambient 1: Music for Airports":
|
| https://www.synthtopia.com/content/2016/01/05/brian-eno-
| tell...
| cuonic wrote:
| 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 wrote:
| 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.
| FriedPickles wrote:
| 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.
| edward28 wrote:
| It would be a real shame if EMF could propagate.
| 77pt77 wrote:
| As long as it's slowly maybe you can catch it.
|
| It it was at the speed of light we might have a problem.
| gumby wrote:
| 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...
| jollyllama wrote:
| They're also more durable; i.e. resistant to running over the
| tube portion with a chair.
| Aurornis wrote:
| > 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.
| saberience wrote:
| What are the recent revelations you're referring to?
| snakeyjake wrote:
| >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.
| mlfreeman wrote:
| I remember putting my ear up to the little holes and faintly
| hearing the audio even without anything plugged in.
| treve wrote:
| 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...
| riffic wrote:
| the inventing company is still around
|
| https://avidproducts.com/2023/12/08/celebrating-70-years-
| of-...
|
| apparently the speaker was in the armrest.
| ben1040 wrote:
| I flew some overseas trips on Delta 767s in the late 1990s
| that still had the tube headphones. I was pretty intrigued by
| the concept, you could hold your hand up to the tube holes in
| the arm rest and hear the music echo off your hand.
|
| Either on the headphones themselves or in the little overwrap
| bag there was a note to leave them on the aircraft when you
| deplane, because they (obviously) wouldn't work elsewhere.
| JohnFen wrote:
| > Seems like the sound tubes ended in the 70's
|
| I was still encountering them in the early '90s, although by
| that time they had become uncommon.
| jmspring wrote:
| This is certainly one of those things that has changed. I
| remember them too. A different era in flying.
| astrodust wrote:
| 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.
| projektfu wrote:
| And, if you're lucky on a longer flight, the audio to a film
| selected to be inoffensive to everyone on the aircraft.
| nessus42 wrote:
| 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.
| vidarh wrote:
| 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).
| AnotherGoodName wrote:
| It was united that I most recently encountered this too. It
| was 2005ish and they flew a 747 with pull down theatre
| screens and pneumatic headphones on an australia-us flight.
|
| Not sure if that was the backup plane or they were just
| desperately holding out to upgrade the fleet.
|
| Having said that anyone that flew just over 30 years ago
| would have likely used pneumatic headphones and watched on a
| shared pulled down theatre screen. It was the norm not that
| long ago.
| vidarh wrote:
| Shared screens was the norm in Europe too, but pneumatic
| headphones is something I've never seen on a European
| carrier at all - not at all ruling out some might use them,
| after all, there are many of them and I've by no means
| flown them all. I wonder, though if it's another case of
| tech that may have been skipped by airlines that e.g.
| didn't add inflight entertainment as early as others and so
| got to "skip ahead" a generation. Most of the European
| airlines I'd have flown with while younger would have
| predominantly flown short-haul flight where inflight
| entertainment might have not been a priority until fairly
| recently.
| typhonic wrote:
| I'm thinking I'm old too because I grew up with telephones that
| had crystal earphones connected with non-magnetic copper wire.
| dusted wrote:
| I recall those being the standard for publci headphones
| everywhere, on planes, busses and hospitals
| lynx23 wrote:
| 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...
| koliber wrote:
| 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 wrote:
| 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.
| dessimus wrote:
| 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.
| phone8675309 wrote:
| 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.
| itishappy wrote:
| 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-...
| sp332 wrote:
| 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.
| typhonic wrote:
| 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.
| denton-scratch wrote:
| 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.
| amelius wrote:
| So they work like a stethoscope.
|
| Would they sound better if they used a liquid instead of air for
| the conduction?
| noobermin wrote:
| Probably not, recall how sounds sound underwater, they do not
| sound like they do above it.
| amelius wrote:
| Sound underwater loses energy in all directions whereas sound
| in a tube with water just propagates along the path.
| timvdalen wrote:
| 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.
| EnzymeFestival wrote:
| What options exist for something superior? These headphones are
| awful
| astrodust wrote:
| Stimulating the audio processing part of your brain directly
| with the MRI machine.
| DavidVoid wrote:
| 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...
| anfractuosity wrote:
| 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.
| birdman3131 wrote:
| 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.
| fluidcruft wrote:
| 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.
| jagged-chisel wrote:
| > 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.
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