Samsung UN46ES6500G E-Manual page 672

have set the brightness on the TV too
high. Try setting the brightness lower.
You can also have loud humming if the
back of your Plasma TV is too close to
a wall or other hard surface. Also, try
rerouting your connection cables.
An improperly installed wall mount can
also create excessive noise.
Image Retention (Burn In) Issue.
To minimize the possibility
for PDP TV