Slight humming, normal?

[KalashnikovAli]

I've had my Dell u2311h for 2 days now and I've only just realised there's a slight humming coming from the screen. I've also noticed that it disappears when I turn the brightness up to anything above 75.

Is this normal?

 

[KalashnikovAli]

Odd..this morning when I switched on the monitor I've noticed no humming even with the brightness on 25. I think it only happens when the monitor has been on for some time.