TV squeaking or is it possible to cover the back of the TV with a cloth, wall, etc.?

Question

TVs

There is an old but decent TV Samsung LE37C530F1WX. I got used. Everything works fine, except for one nuance. When the screen is dominated by dark colors or dull black frames, the TV will start beeping/buzzing at high tones. The same thing happens if you turn on the low brightness mode. Naturally, I'm going to give it to the master, but there is no time and opportunity yet. The sound itself is not particularly audible when viewing, but in the evening, when the volume is at a minimum, the sound infuriates.
Actually the question is whether it is possible to muffle it with something like fabric. More precisely, there will be no problems if it is framed around the perimeter, let's say, in acoustic foam rubber, which I have. So the sound is almost inaudible, but I'm more worried that it does not overheat or heat the material itself.
The question is strange, but someone else's opinion is interesting)
Thank you