Don't think its vibration. That effect is very small. If he is really aware of the fuzziness then its probably mic'd improperly. Try playing the CD on another system. A car CD player would be just fine since they tend to emphasize the vocal band. If it sound clear then you have a system problem. One other possible problem is a blown midrange speaker.
Fuzzy Lyrics
I am new to the technical aspects audiophile world but I know what music is supposed to sounds like. I have two CD's where the vocals start to sound fuzzy. Is this the recording or something wrong in my meager system. The two CD's are recent recordings, one made earlier in 2000. At first I thought it was the recording because the first CD gets fuzzy in the exact same place of the same song. Please help.