it doesnt have to happen with high volume...i can be listening moderately and it will happen (been happening for 20 years now)
dont LCD monitors have refresh rates also? why wouldtn it happen to these type of monitors?
so if this also happens to intersection countdown timers, then the displays are also going through a duty cycle?
dont LCD monitors have refresh rates also? why wouldtn it happen to these type of monitors?
so if this also happens to intersection countdown timers, then the displays are also going through a duty cycle?
Just play some bass note tests between 30 and 60hz. The bass pressure waves could actually be compressing your eyeballs and changing the focal length of your retinae in sync with the refresh rate. Try it with the windows up too. Wow, interesting stuff. I've seen it happen a few times and wondered what was causing it. Now when I get my bass amp reinstalled I'll try it out too. 
It does the same thing when you're looking at a trace sweeping across the CRT of an oscilloscope. You can get the same effect by eating something really crunchy while looking at the scope. You have to have the timebase set to ~2-5ms.
As has been said, it is due to your eyes vibrating due to the bass and distorting your vision. This causes the flickering effect on the CRT much the same way a wheel looks like it's spinning backwards in fluorescent or flickering light.
You can recreate this effect by blowing a raspberry at your monitor. The vibrations from your raspberry blowing vibrates your eyes in much the same was as the bass notes from your music.
You can recreate this effect by blowing a raspberry at your monitor. The vibrations from your raspberry blowing vibrates your eyes in much the same was as the bass notes from your music.
Ah, well you know. Isn't that...... Normal? 😀
Actually I think I read it in a kids science magazine years ago. (CSIRO Double Helix I think)
Actually I think I read it in a kids science magazine years ago. (CSIRO Double Helix I think)
My take on this:
Back in the day when I was campaigning an SPL vehicle I noticed that I could affect florescent lights.
I came to the conclusion, after discussion with a friend and electrical engineer who witnessed the effect that it was being caused by 60Hz disruption.
Meaning that because the common household 115v AC circuit runs @ 60Hz and therefore lights and monitors switch on and off at 60 times per second.
I found that if you played a note at 60 Hz OR octave (+or-[30Hz or 120]) at extremely high spl (155-160+) that it did in fact cause a disruption in the lights.
I have always attributed it to the "backward rolling wagon wheel" affect (an old movie was shot with the spokes of a wagon that appeared to be going backwards during a chase scene because the spokes reached the top of the wheel slightly ahead or behind the speed of the frames of the film, and figured that the soundwave @ or near the same as the light cause it to affect its performance.
Sounds crazy, but I have seen it.
Back in the day when I was campaigning an SPL vehicle I noticed that I could affect florescent lights.
I came to the conclusion, after discussion with a friend and electrical engineer who witnessed the effect that it was being caused by 60Hz disruption.
Meaning that because the common household 115v AC circuit runs @ 60Hz and therefore lights and monitors switch on and off at 60 times per second.
I found that if you played a note at 60 Hz OR octave (+or-[30Hz or 120]) at extremely high spl (155-160+) that it did in fact cause a disruption in the lights.
I have always attributed it to the "backward rolling wagon wheel" affect (an old movie was shot with the spokes of a wagon that appeared to be going backwards during a chase scene because the spokes reached the top of the wheel slightly ahead or behind the speed of the frames of the film, and figured that the soundwave @ or near the same as the light cause it to affect its performance.
Sounds crazy, but I have seen it.
Clipped said:what causes the TV monitor at a drive through window to jiggle and bounce around when you look at it when playing heavy bass?
i know it is not really moving... is the bass causing the wavelength of light to be diffused via the jiggling eyeballs?
why dont other types of light behave this way? for example a stoplight...
someone else please tell me youve seen this too...so i wont think im crazy after all these years...
As others have stated, it is the result of vibrations literally moving your eyeballs around in their sockets.
Now for the reason. The LEDs are multiplexed at a relatively low refresh rate. Take a RED LED clock and pick it up...shake it up and down - the segments appear to bounce out of the chassis. Scan your eyes quickly back and forth across the back of any 2003+ Cadillac vehicle (and some Fords); they foolishly chose a low refresh rate for dimming their taillights. It drives me nuts, incidentally. You'll see a swath of LED segments across your field of view as you scan your eyes.
Most LED Christmas lights do the same.
So do cheap "Beta Brite" moving message signs. The big billboard signs do not.
Even LED or Xenon based radio tower lights do this.
So why don't LED traffic signals (other than Walk/Don't Walk indicators) do this? Simple, they choose a high refresh rate. They are switching on/off above 500Hz to eliminate flicker.
Clipped said:
Because LCD displays are first lit by fluorescent tubes switching at 50kHz AND LCD displays don't actually refresh by going all black and updating sequentially as LED screens do. The pixel controllers change state then the pixels refresh to the new state. If the LCD never refreshed, it would eventually "go white" and display a big white sheet. Think of what a LCD-based calculator looks like when the power is off.
A simple way to demonstrate (or disprove) that this is a physiological effect would be to stand *outside* the vehicle, looking through the windows (across the 'sound cell' of the vehicle) at the monitor (or whatever).
I would expect there to be no observable effect on the image.
I would expect there to be no observable effect on the image.
I noticed this effect 20 years ago in front of radioshack , I had 2x EV 15b's driven by a 3 piece zapco system on my bug , radio shack had only a CRT's when the subs hit all the crt's would squat , I figured it was something envolving vibrations on my eyeball , but it took 20 years and a educated awnswer from richie00boy to solve it !richie00boy said:
thanks
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