Unexpected sounds

Yesterday morning, I turned on my laptop and while I was reading my mail, I had a one or sound bytes come out of the speakers. since I keep the volume real low, I thought maybe it was stereo in background. So I turned of the stereo and turned up the volume and i didn't hear it again. (sounded like a rush of air--beach)
This morning it happen again, but this time it came a second time and third time. I started timing it to see if was happening at the same time, and it wasn't. 48 seconds, then 3 minutes 10 seconds.
I started looking at things that I have put into my save folder, because I know I had NOT downloaded anything for last week, except one thing,and then that was Malwarebytes software.
I did a defrag, and it came that 2 files could not be defraged, and they ARE with google desktop (go old google---I really like google, but man, problems) so I deleted the google desktop icon in my systems tray--(lower right hand next to the clock), and since then the sound has stopped!
I saved the defrag file and I think(?) I got it so it will show here.
The sound has stopped for over an hour, and I did a restart to see if it would come back and nothing.
But i was wondering if someone could explain this in real simple terms.
thank you
scott