Speaker interference?

I've heard they can interfere but they can't cause a mode switch or reset anything ...can they? What happened in Nashvegas is staying there but it did involve close proximity to speakers into the wee hours.

11 Comments

NOT magnets

by donr - 2014-06-22 02:06:14

unless you passed out totally smashed w/ your upper body draped over the back (Magnet) end of a whopping speaker.

If you felt anything it was a phenomenon called "Resonant vibration," or something like that. Two well known EE Geeks have written extensively in here about it.

Just because I'm really a nice guy, I'll go get it for you - again. You may sit there & nurse your headache. Do you need a fresh ice bag?

Don

Here's all the info you need - & then some

by donr - 2014-06-22 02:06:50

Tracey: I'm Gonna.....
Comment posted by donr on 2014-03-29 23:24.
.....disagree w/ you on this one.

There is not a permanent magnet that humans could carry strong enough to affect the PM in the 20th row. Even the superconductor magnet in an MRI will not get you at that range.

This one is pure & simple vibration affecting the RR device in the PM. Medtronic uses an accelerometer to sense motion of the upper body. That is nothing more than a very small mass of metal attached to a spring & a sensor. Just like the devices in the guidance systems in missiles & navigation systems in aircraft. If the body moves at all, whether by its own muscle power or if it vibrates as Ksig describes, that accelerometer is going to move & the sensor will generate a signal that the computer thinks is exercise or motion of the body.

In this case, however, somewhere in the frequency of that heavy sound was a vibrational frequency that matched the mechanical phenomena called its "Natural Frequency." At that point the little mass has the greatest movement & Will really generate a wicked signal. Unfortunately, that signal will most likely be changing much faster then the body ever moves & the PM gets confused & drives the RR function nutso.

My guess, therefore is that she was feeling a truly confused RR device trying to affect the HR.

Now the way she described the feeling, she felt it in her chest. Also buried in that bass was a frequency that matched the Natural Frequency of her body cavity - most likely the lung cavity. For sounds, it is called the "Resonant Frequency." Blow across the open mouth of a Coke bottle (If you can find one) or a Budweiser bottle. The sound you hear is its resonant frequency. Same thing w/ the chest cavity. You feel it vibrate at its Resonant Frequency.

Donr


Thanks
Comment posted by ksig on 2014-03-30 16:22.
Donr your explanation makes a lot of sense to me. I knew this had to be a sound engineering problem and not a problem with my heart. Your explanation was easy to follow and I appreciate your time to write the explanation.

TraceyE: I knew I was too far away from the speakers for the magnet effect to take place. I knew it was vibrating sound that was causing my discomfort. Since I am 100%pacer dependent, I am always fascinated by things that effect my pacer/heart.

I appreciate the quick responses from this community. Best to all of you.
ksig

A Small Experiment for you to try...
Comment posted by donr on 2014-03-30 18:45.
.....Ksig: Try this. I did it today & it worked.

If you'd like to learn the resonant frequency of your chest cavity, fill your lungs w/ air, close your mouth & start "Humming " at the lowest frequency that you can. Vary it up & down slowly. If your vocal cords are capable of going low enough, the instant you hit that frequency you will feel your entire chest start vibrating & the sound will instantly become louder. I don't think you can activate your PM's accelerometer this way. I assume you are a woman, so there is a fair chance that your vocal cords will not be able to go low enough. But any man out there short of being an Irish Tenor should be able to do it.

Sitting in the audience so close to the speakers, they generated a LOT of sound energy & when it hit the resonant frequency of your chest, it was significantly amplified.

Anyone out there old enough to remember Bowser, the bass member of the TV rock group in the US called Sha Na Na? He could probably generate enough voice energy to activate the accelerometer.

I vividly recall a Humongous church organ that was capable of putting out enough energy at the correct frequency to make the interior volume of the building resonate. The organist always hit that note after the sermon to wake everyone up. It was practically inaudible to the ears, because it was too low, but you sure could feel it in the chest & feel the air in the building vibrate.

For the rtruly curious, if you want to see what a small amount of energy coupled into a steel structure can do, Google on "Tacoma Narrows Bridge Failure." Back about 1940, the wind hit just the right velocity perpendicular to the bridge & it started vibrating & destroyed itself. There should be a video of that disaster on some web site.

Every engineer in the world knows about that disaster.

Don

no reverberation can be duplicated ;(
Comment posted by ksig on 2014-03-30 20:03.
Hi, Donr
I tried the experiment to no avail. My tone is too high as I am a female as you guessed. But I had fun trying! Funny you talked about the ShaNaNa group. In the 70s I saw them in person and have a faint remembrance of Bowser's low voice.

All in all, I had a very interesting experience and wanted to know the mechanics of it all. I appreciate your time and interest.
ksig

And to put a name to it
Comment posted by KAG on 2014-03-31 12:03.
it's called Acoustical vibration. Don gave a very good explanation as usual. Same effect happens when you're at a stoplight and a car near you has mega speakers blasting out the bass. You can feel the vibrations.

No wonder it can make you loose your hearing.

@donr

by Bostonstrong - 2014-06-22 04:06:06

Feeling like 10 miles of bad road...and no I do not have a headache or a hangover, just exhausted.. Kept it classy.......as always. Probably sleep deprivation.

That 10 Mi of bad road.....

by donr - 2014-06-22 04:06:23

.....was it wet? Dry? full of potholes? Washboarded? Rutted? Gravel? Hilly? C'mon, now, be more specific. Inquiring minds NEED to know.

Don

All the above

by Bostonstrong - 2014-06-22 04:06:53

Probably didn't help that I had food poisoning Thur night, got very dehydrated, left for Nashville Fri am and had a near syncopal episode when I stopped and got out of the car. Got salt and Gatorade, drove rest of the way to Nashville. Met my friends, did way too much walking, then went out with friends for some live music. And dancing. Got back to the hotel around 2 am, and we were back on the road by 8:30. Got home around 11 last night. I was hoping it was the speakers because surely I am not old enough to be this tired from a couple days of fun?

Too Old? Lemme see, now...

by donr - 2014-06-22 05:06:45

.....You're over 30, last I knew. Yep - you'd feel like you just crawled out of the floor drain in an ICU after a night that sounds like that.

Even worse - you DROVE. What do you think you are? A Teenybopper & indestructible?

How the &^%$% do you get food poisoning from chocolate?

Don

speakers

by Alma Annie - 2014-06-22 10:06:40

Sometime ago I was standing right underneath a speaker at an outdoor funeral. My head was just below it. I began to feel queer, dizzy and had the feeling I might pass out. Seeing a seat, I went to sit down and within 15 minutes was fine. I posted my experience here and was told it was the magnets inside the speakers. I didn't know speakers had magnets. So was it that or the vibrations? As I am somewhat deaf it was not too loud where I was standing.
Any more info would be interesting.
Alma Annie

Age

by Bostonstrong - 2014-06-22 10:06:55

No one is too old for music especially in Nashville. Ate tilapia and salad in the hospital cafeteria, two hrs later I regretted it. Bitterly. On the bright side I got two pieces of exercise equipment from the hospital to put in my waiting room. Weather, transportation, money...just some of.the many excuses I hear from my patients who refuse to move. I've just removed 3 barriers.

Didnt feel bad

by Bostonstrong - 2014-06-23 01:06:22

I didn't feel bad at all close to the speakers but the next day was dragging and feeling like I did before the pacer. Ive heard late nights can cause this feeling the next day as people age. Just didn't think that would ever mean me! Because I have some clients who are rock stars and I am occasionally backstage with them my EP told me to stay 10 feet away from speakers. I would trust Don more than him on this issue.

close!

by Alma Annie - 2014-06-23 09:06:40

I was really close. A long time ago now, and I did not realise at the time that my 'funny' feeling could have been the speakers. I had the same feeling when going into court to support a son, it was insisted that I had the wand, and they refused to give me a pat down. I felt queer then for about 15 mins, then I was ok. I also felt the same when I went close to a generator. I did that on purpose to see what would happen, so as soon as I felt odd, I backed off and was ok.
Alma Annie

How close is close?

by donr - 2014-06-23 12:06:28

Alma: ALl speakers have a big magnet in them. They are permanent magnets, so they are essentially "On" all the time. I recall that Electric Frank once picked up a huge speaker from his jeep & carried it into the house - w/o ill effect. His chest was right next to the magnet.

You will not get vibrational effects from a speaker unless it is VERY heavy in the bass frequencies. And it must be a very big speaker to do it.

It's kinda tough to speculate when you have no idea what kind of speaker you had your head under.

If it was a big horn shaped speaker & your head was right under it, you could have been feeling vibrations from it. Also, it is completely possible that it was the magnets.

Donr

You know you're wired when...

Your signature looks like an EKG.

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