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Re: Weird Behavior: French Horn + Monitor

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I used to play second chair French horn with Bob in high school. The talent gap between first and second chair was IMMENSE, which is why I got a BSEE at UC Berkeley and Bob went on to get his PhD in music. I can't rule out the physio explanations but it's possible that there are components in the monitors that are exhibiting microphonic behavior. It's common in vacuum tubes (CRT is a vacuum tube) but it occurs occasionally in all sorts of other components, both passive and active. The acoustic forces cause a change in an electrical property of a component and in turn the behavior of a circuit. The change is often proportional to the amplitude and sometimes frequency of the acoustic wave that impacts the affected component. 
See: https://en.wikipedia.org/wiki/Microphonics.

Mark Meltzer
Palo Alto CA

On Monday, October 3, 1994 at 1:08:15 AM UTC-7, Bob Dickow wrote:
> This question could go to any hardware/monitor/physics/accoustics
> newsgroup, I suppose...
> 
> Sometimes while playing certain notes on my French horn in the
> same room with a running video monitor or TV, I can set the
> display into a vibratory ripple, or sort of wavy distortion.
> 
> My question is, why would sound waves affect the video display
> so? My hypothesis is that maybe the whole cathode ray tube is
> going into syphathetic vibration/resonance, but the effect seems
> rather dramatic.
> 
> --
> 
> --Bob Dickow (dickow@crow.csrv.uidaho.edu)

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