A buzzing sound could come from a cooling fan or the electricity used to power the TV. Color wheels on DLP TVs could also make buzzing or humming noises.
People should try sitting farther away from the TV if they can hear humming. Reducing the volume, contrast and brightness can also help.
DLP stands for Digital Light Processing. It's one of the most popular technologies for rear projection televisions. White light passes through the color wheel to produce colors. With these TVs, people should only be able to hear the color wheel when turning the TV on and off. This is because it changes position. A TV that's humming loudly or constantly needs repair or replacement.