it bullshit man,
the only way i could imagine it doing anything would be if you had very low frequency bass sounds which might cause fluctations in the air enough to rock ur plants back and forward, making ur plants stems stronger. the same way that a regular fan would.
as for music as in songs, there are other posts talking about this, use the search button, i believe mythbusters did it if that means anything.... and it came up as pointless
peace