Random grinding noise on iPod Touch 4g

I am an iPod touch owner with all of my software up to date. A few months ago, I was trying to reinstall GarageBand, and it told me I didn't have the space for it. So I made plenty of space (I even checked in Settings>General>About) and went to try again. It didn't do anything for a while. After about 10 seconds, I tried to push it again, when it made a very quick sound. It's like two quick grinding sounds, and then bubbles. The grinding sound sounds like a wooden chair on a hard floor. Anyway it made the sound and told me I didn't have enough memory, and to go to settings, and had a settings button, and a cancel button. I pushed settings and I did nothing. I tried again but this time pressed cancel, and got the same result. I've restarted my iPod several times, and looked for updated software, but now, for quite a while, my iPod makes that sound sporadically, without any specific reason, even if I'm in safari, playing a game, and even when it's resting.

Does anyone have an answer? Can I install GarageBand?