I found it a little troubling, but I finally noticed that my BC-U1 makes capacitor noise whenever it's in use. I thought it was a fault, but apparently all BC-U1s (supposedly in the world) have capacitor noise coming from the charger.

Does your BC-U1 make capacitor noise? If not, look at the box for your BC-U1 and tell me the revision code after the model number.

I've dealt with five or six different chargers and they all make "the noise" as well as my laptop bricks etc.

Sometimes I envy people who cannot hear those frequencies.

Mine does. Seems to go in time with whatever the green light is doing.

Second what Marcus says.
It's synced with the LED and quite a whiny wide ranging noise.
How anyone cannot hear it is beyond me.

Perhaps I'm still quite young....
Ha, I still have perfect vision, but a perorated eardrum that farts and bubbles so loud that others can hear it!

I have 4 chargers that are absolutely silent.

Maybe it's my ears but...
I seem to hear more noise when plugged into 220v than when plugged into 110v

Assuming the noise we hear is in somehow related to the mains frequency, yes there would be a difference between a 50Hz and 60Hz supply.

I'm not suggesting for one second that what we are hearing is at 50Hz, but it is perfectly possible the whine we hear is somehow related to the mains frequency. In the days of CRT TV's some people from 60Hz countries often complained that 50Hz sets made a high pitched noise.

The whine is a high pitched whistle that comes from the inductors vibrating within the switch mode power converter. It operates at a frequency much higher than the mains frequency, somewhere around 15-20khz. It pulses on and off as the battery is charged in short bursts. All of mine make the same noise, have done since I got my first one over 4 years ago with my original EX1.

I envy all these people who can hear sounds in the 15 to 20,000 hertz region. My hearing stops at roughly 12,000 after 20 years of concert photography. Not to mention the constant hissing and peeping in my left ear. Should have photographed birds and bees.

Or should have used earplugs? :)

I have a pair of Etymotic ER20's on my key chain, in my camera bag, in my car, in my guitar case...

The Dolgin Engineering charger is silent. It's a nice piece of gear and quite rugged. It does not however power the camera:
Battery charger TC200-EX 2 position [TC200-EX] - $289.00 : Dolgin Engineering, Camera Power Solutions (http://dolgin.net/zen_dolgin/index.php?main_page=product_info&cPath=1&products_id=47)

Or should have used earplugs? :)

I have a pair of Etymotic ER20's on my key chain, in my camera bag, in my car, in my guitar case...

Quite right, Zoran. I use earplugs now, but too late. But it's not all down to video: I've also played in a band for over 10 years and we only knew one setting for the volume knob... Silly, but true.

Many LCDs emit a whine in the 15000 Hz range. My EX1 charger whines as does my Maha AA/AAA battery charger.

The percentage of charge indicator in the lower right of my charger does not light up when charging to show how far along the process is. Anybody else have this quit working? Any fixes?

It's never worked for me.

It makes the same sound as my Flux Capacitor ;)