T61p bouncy sound

I have the oddest issue in my new computer.
Every once in a while I get a low bouncy sound from the computer, as if it was a small plastic piece that hit against something and bounced. It happens randomly bouncing once or twice each time. I tried moving the computer a bit to try to tell if there's something loose, but everything seems in place.
I can't even tell if it's played by the speakers or if it's hardware.
The computer works fine, there's no problem but this issue has me intrigued.
does anybody has the same thing happening and/or know what it is?

 

Hard disk?

 

Could it be the hard drive? Do you have the Seagate? That can be a little loud according to people. It's been described as the sound of marbles dropping or rolling.

edit: looks like John B. beat me by a second.

 

One way to at least find out if it's the speakers or the hardware would be to mute your speakers for a while. It sounds more like a system sound played through the speakers, but the quickest way to rule it out would be to just use the notebook without sound for a few days.

 

Well, now that I think of it I have used the computer without sound in some occasions and it happens all the same, so definitely not speakers.

Magiste: exactly like marbles dropping. I forget which one is my hard drive, although I'm pretty sure it's a seagate. It's the 100gb 7200rpm one. I don't have my computer here to check.
In any case the hard drive is pretty silent, it's just that sound (and it's kind of a pleasant one LOL)

 

I think it's likely the Seagate hard drive then. You can do a search on T61 and marbles (or T61 and hard drive noise) on this site and pull up lots of threads on the subject. I don't think it's anything to worry about, especially if the sound doesn't bother you.

 

Cool, thank you!!
I didn't do a search because it seems so random that I didn't know what criteria to use.

 

It is either the fan or hard drive.