Why Are Some Songs Sounding Garbled When I Burn CDs?

Hey everyone! I'm trying to burn a CD on my Mac using an LG slim DVD burner and some CD-R discs. Most of the songs copy over perfectly, but a few of them end up sounding garbled. I've tried burning the CD with iTunes, Finder, and Express Burn NHC, but I keep getting the same messed up sound on those particular tracks. The audio sounds fine on my computer before I burn it; the issue only happens after burning. Does anyone have an idea of what might be causing this?