Thus sparking the engineer’s natural distrust of authority figures.

Sounds ingenious but I don’t quite follow the story. Why would a stewardess make you stop? Was there some system where you had to pay for headphones separately to hear a movie? I’m pretty sure all I remember are headrests having standard 1/8” audio jacks.

I used to just pull the armrest up next to my ear and listen directly out of the hole.

I would've moved you up to First Class for being so inventive.

> (always wondered why it wasn't just a stereo jack)

Either because they didn’t want you to take their headphones from the plane, or so they could charge for use because you couldn’t just plug in your Walkman headphones.

Or both.

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.

In my "maybe I'll need it some day" pile, I still have the two-mono-plugs to one stereo jack adapter I bought at Radio Shack so I could stick it to The Man. I think I only used it half a dozen times.

> 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.

> Seems like the sound tubes ended in the 70

I'm 40-ish, and I remember them as a child, so they were definitely still kicking around in the mid to late 80s, most likely on KLM and Pan Am, that were the airlines of my childhood.

the inventing company is still around

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

apparently the speaker was in the armrest.

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.

And, if you're lucky on a longer flight, the audio to a film selected to be inoffensive to everyone on the aircraft.

Spitballing:

Cost: one speaker and tubes was probably cheaper than 200.

Weight: old headphones were chunky, see above.

Comfort: not wearing giant chunky headphones you weren't accustomed to might have been preferable

Breakability: pneumatic headphones were harder to break, cheaper to replace

Stealability: passengers would have no reason to steal the headphones, and if they did it was cheap to replace.

All of these go away as proper headphones get increasingly small and cheap.

If Bluetooth headphone batteries can produce significant heat for 8 hours we would have discovered a lot of free energy :-)

I've only watched a little bit of Huberman, but I can't take him seriously because:

a) he's obviously done a LOT of steroids or something, which aren't really great for you

b) At least half of what he says appears to be made up woo-woo nonsense

What are the recent revelations you’re referring to?

As long as it's slowly maybe you can catch it.

It it was at the speed of light we might have a problem.

A button for garbage disposal before you have a chance to dry your hands? What does this button do, activate some pneumatic tube system so you don't have to carry trash to the bin?

I sympathize with that, more than once I've eyed mine's regular-light-switch and thought: "Surely the remaining water on my hands has too much surface-tension to go through any of those tiny gaps in the plastic... Right?"

I believe this is required by code in some places, depending on the location of the switch. Mine is inset into the counter top, so plenty of opportunity for water to pool around it which I think would rule out an electrical switch.

Was it good? Do you have the title?

FILO is not the standard method of maintaining one's stock of clothes? How else does a person mange wear leveling?

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.

Taking off metal jewellery in the scanner is about the worst thing one can do - it’s then loose. It would be very unlikely to move from a clenched fist, even if ferromagnetic. However having it escape your hand isn’t that difficult.

I’ve seen most these things play out. And as you say, it’s exactly what the call bell is for.

Tungsten carbide jewelry is a mixture of tungsten carbide powder and a metal binder, typically cobalt or nickel. The metal binder is electrically conductive and thus susceptible to the induction heating you felt.

What you were experiencing was a) probably real and b) due to the conductive properties of the ring , not magnetic.

Oversimplification: Moving a conductor in a magnetic field or vice versa indices current in the conductor , resistance in the conductor results in heat.

The main field in an MRI is static but there are a lot of other fields moving around…

Similar happens on your body also (eddy currents) and deeper tissue gets energy which has to be controlled for - it can cause stimulation in peripheral nerves and heating .

> little to no magnetic effects

Whether or not it’s a conductor is probably more of a concern. The loop likely wouldn’t be large enough to cause any drama though.

One of the things MRI do to create images is to pulse magnetic fields during imaging. These pulses are far weaker than the main field but will cause vibration of metals due to Lenz's and Faraday's laws. As the magnetic field changes it induces current in the ring, current in the ring interacts with the magnetic field to produce a (small) force on the ring. If you were getting a head/brain scan in a typical MRI your hand will lie near the locations within the scanner that see the largest swings in magnetic field. Beyond the vibration, rings are generally too small to be a heating issue even at 3T.

Best practice for at least a decade is to always remove all rings and all jewelry and failure to detect rings or other jewelry is generally seen to indicate a problem in screening. That is... if a radiologist sees evidence of a ring on the images there better be an explanation. The reality is that particularly older people have not removed their rings in decades and their joint disease may have expanded so much that it simply cannot be removed and the risk/benefit doesn't justify damaging the ring nor denying them the benefits of a scan. But if the patient can't take the ring off, the magnet wont either.

Just for reference, people get head scans with braces pretty regularly and it's not considered a safety issue. Braces and rings can affect image quality though so that's usually the concern. So if the ring is near the body part being imaged you'd probably be asked to remove it because they'll easily cause undesired issues (in, say, roughly a 3-6inch radius) that can result in images that radiologists deem unusable for making a diagnosis.

I'm pretty sure it was the 2008 ISMRM meeting (small chance it may have been 2003). I don't think it was actually submitted, because I couldn't find it in the proceedings even back then. I think whoever it was smuggled the poster into the hall and hung it among the others as a prank. I'm pretty sure the dead salmon fMRI poster was also there at the time but I can't remember if that was in the proceedings. The dead salmon fMRI did end up being published though and making quite a stir.

Well it says the headphones are sold by the MRI company:

> The CRBN headphones are integrated into the Lumica AV system from SMRTImage that provides images and movies

Maybe you can get more info out of them: https://www.smrtimage.com/