steptide explanation of the sound bar is a good one. i found that most sound out of the standard speakers on the tv is pretty weak, depending on the room. we have a great room that our main tv is in, and it absolutely needed the sound bar. it's also on an ARC, so the sound automatically goes through the soundbar once the tv is turned on. for mine, it takes a second, so i first hear it through the tv, and after about 3 second, through the sound bar. the sound is significantly better. it's almost a necessity for normal sound in certain rooms. no where near as nice as surround sound, but much less expensive.
i don't have a sound bar in my home office, but i don't have any problems with audio, mostly (i think) because the room is smaller. i've also heard the newer tvs have improved the standard speaker sound quite a bit.