Subject: Capacitor charging and plasma speakers.

When a high voltage capacitor is charging, sometimes you can 
hear a whistle. Where does it come from? Is the frequency of the charging 
current the same as the frequency of the whistle?  Is the effect like that of  
a sound transducer?! Is the mechanism related to the way that plasma speakers 
work? By the way, how do plasma speakers works?

Re: Capacitor charging and plasma speakers.