N56jr / n56 chassis vibration, speakers issue?!

Hi Guys! I'm from Poland and sorry for my English.

I just bought my brand new N56JR-S4013H... and i have one (for me, it's really problem) question about speakers... i try to update bios, drivers, with and without sub, change the settings in maxxaudio & windows and nothing... when i play (no matter that are music, youtube, movie, game etc.) in some songs, in the same time (no matter when i play this song) i hear specific thing... my speakers give me the sound like chassis vibration or something like that. Everything else is just amazing - crisp, loud and clear.

Can You test in yours machine? I upload three of songs where i have this problem (in background). The volume of "vibration" are bit low with lower volume level but is still exist and disturb. Can you check it also on Asus Screensaver (it's with audio) because i have the same "vibration". I'm was on the store where i buy notebook and on the second N56JR it's the same. I've tested on Win8, Win8.1 - the same.

Maybe this is normal but i'm worried about this. On output jack (external speakers or headphones) it isn't exist.

http://speedy.sh/d5xH4/Dna-Niewidzialni.mp3 or http://ulub.pl/szukaj.html?q=dna+niewidzialni 0:09-0:20

http://ulub.pl/szukaj.html?q=andrea+bocelli+time+to+say+goodbye 0:20-0:22

Serebro - Malo Tebya.mp3 - Speedy Share - upload your files here 0:00-0:07

To download from speedy click link above the five stars.

I have answer from one person:

"@skoczi

Before I get interested in N56JR I've bought N56VZ with the same chasis and I got exact the same problem with chasis like you. I were worried about it too didn't know if it exist in every laptop but it seems like it does."

Maybe it's not most important thing in my life but i must pay for my notebook 1399$ and i wants to know what is with my hardware.