Audio / stereo

Yes

by NiceNiecey - 2017-09-23 00:58:46

I, too, have notice "activity" with my PM when music is loud, especially with a pounding rhythm.  I concluded or read here on this site that rate response kicks in when subjected to the heavy bass sounds.  It's nothing to worry about but it is a curiosity!

Niecey

I wrote this back in 2014: Enjoy!

by donr - 2017-09-23 08:05:31

Tracey: I'm Gonna.....

by donr - 2014-03-29 11:03:17 Edit

.....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
 

More trivia from the deep past

by donr - 2017-09-23 08:06:44

A Small Experiment for you to try...

by donr - 2014-03-30 06:03:45 Edit

.....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

Pedigree

by donr - 2017-09-23 08:10:58

FYI, the above two extracts come from the thread listed below, buried deep in the bowels (NOT to be confused w/ bowls) of the archives.

"very odd feeling at a concert":

by ksig

2014-03-29 04:03:

Donr

Love it!

by Gotrhythm - 2017-09-24 11:49:46

Donr, 

I just love your explanations of things. You have a true gift for translating engineering subjects into terms the layman can easily grasp.

In one of life's little serendipities, as I read your replies, out in the street a motorcyle growled by. The windows are closed and I noticed feeling it in my chest as much as hearing it. Somewhere in it's sound must have been my resonant frequency.

Neat.

And yes, I too have sometimes felt my pacemaker kick up in response to heavy base. I like the sensation. It adds a little extra thrill to the music. Now I know what to call what is happening.

To Rhythm:::

by donr - 2017-09-24 14:09:25

Funny coincidence.  I just read your comment, & while I was sittig here contemplating my navel, thinking of some cute remark to return, Something outside occurred & I could feel the vibration in my chest.  I could also HEAR the sound as it increased to a max - the resonant frequency - then decreased & disappeared.  I only FELT it for the short interval when it was at the resonant frequency.

Remember the "Old" days of tuning a radio? You would have the knob connected to the Station Dial.  You'd slowly turn it till the station was at its loudest.  You were actually adjusting an electrical component called a "Capacitor" so that it was at a resonant electrical radio frequency corresponding to the transmission frequency of the station.

Donr

rhythm

by rcescato - 2017-09-25 08:33:24

I was just at the Scorpions concert on Saturday. I did not feel anything different the whole concert!  I do go to a lot of metal shows and have not had a problem

                   Rich