Crunching noise from the optical drive

Whenever I try to insert a CD into the disk drive, I get the noise from sample-1 under the "Inserting a disk" section from the Apple support link Mac notebooks with optical drives: Noises from the optical drive - Apple Support

I can't find anything on how to fix this yet so I'm hoping somebody here can help. I bought this macbook secondhand off of somebody on craigslist almost a year ago so I have no way to contact them anymore. I've only used this computer as a backup so I've never known this problem existed before now.

Any thoughts?

Edit: The CDs won't play and ejects after about 30 seconds of making that crunching noise without showing up anywhere on my drives.