macbook making thumping noises

so i'm not quite sure how to explain this i tried googling it but nothing came up. my macbook is making this weird thumping noise and and on youtube or any other website that streams videos while i'm watching the video pauses along with the sound and has this thumping noise. i really don't know what this is happening. would this be a harddrive failure or sound card or what. it's been over 1 year so i'm out of warranty if anyone knows what i'm talking about do you know what the problem could be and how much it'll cost to get it fix. and i also reset the pram and ran disk utilities is there anything else i can do before taking it to the apple store. thanks.

What did you run through DU - verify/repair permissions or verify/repair disk? What did it return?

If the "thumping" is more of a clicking sound and coming from where your HD is, it could very well be a dying HD. On my MB, the HD is under the right hand palm rest, next to the battery. I say this not knowing if the placement of the HD is different for you.

i ran the DU i don't remember what it did but i'll run it again and the thumping noise is sort of coming from the left hand speakers oh and also when im on itunes my music would cut out and i would hear the thumping or crackling sound which ever it is i can't really describe it. thanks for your fast response.

Sounds like speaker issues if it is crackling coming from your speakers. Does this noise only occur when you are playing audio (either through a song or video)?

that's what i thought too but the noise occur even when the speakers are mute and cuts off when i'm playing a song or on youtube or other streaming sites. i'm ran the du and it says file has been modified and will not be repaired is there anyway i can repair? thanks again.

also says 'the volume mac HD appears to be OK.'

i also installed smartreport and it says 's.m.a.r.t. condition not exceeded, drive OK' but i'm not sure how reliable these apps are.