New T.V. sounds.
Hatfield has it right.
I have one that has other "features", they are things like "music", "theater", etc... Play with those too, I found it makes the sound come out of the tv speakers in different places. Those places make the sound bounce along wall or furniture, what have you, and it could be your sound is bouncing off something that creates an irritating issue. Could be a window, a glass picture frame, the walls, you name it.
Each time I move to a new apartment I have to spend a week or two trying to figure out which setting is best for the new place. It is irritating, but once I find a good setting I leave it there.