ROCK/POPR.E.M. - Monster (Warner Bros.): After several successful. albums that featured folksy tunes, R.E.M.'s new release - Monster -
is a switch back to a rougher-edged rock-and- roll. The result is a refreshing change from the group's last, more-subdued album ``Automatic for the People.'' Guitarist Peter Buck has traded his mandolin for an electric guitar and jams on such songs as ``Circus Envy'' and ``I took Your Name.'' Singer Michael Stipe's vocals are almost impossible to decipher in many songs, however, due to the sound mix. Still, fans should be used to that; the group has never made it a practice to reveal their lyrics.