It seems to be a part of the human condition that having established a specialty, we hanker to do something else. And far be it from me to say that we shouldn't. But speaking as a classical music critic who also listens to lots of rock - and who wishes that more rock fans found classical music exciting as well - I must confess that I find many of these crossover incursions dispiriting.

Why do so many pop musicians aspire to write classical music? The hunger for critical recognition is not apparent in other artistic endeavors. How many action film directors use their Hollywood prestige to make a probing drama of the human condition? Tom Clancy doesn�t try to expand his genre to produce insightful novels about human relationships in contemporary society. Neil Simon doesn�t attempt to write brainy mind-bending fantasies dense with allusions. They�re content to work successfully within their own fields.

For some reason, popular composers want the approval of classical critics and audiences. This may have had some validity 80 years ago, when the �music critic� at the paper only reviewed classical concerts; in fact, the designation �classical music critic� is a fairly recent title in journalism. In our era of cultural relativism, where professors get tenure publishing books on Madonna or Buffy the Vampire Slayer, the hankering for classical acceptance is unnecessary, an anachronistic throwback to the days when the only music that was taken seriously, that was considered respectable, was classical music.

Yet they keep trying: Paul McCartney, Andrew Lloyd Webber, Billy Joel, Elvis Costello, David Byrne. For whatever personal reason, they keep assaulting the ivory tower. And unfortunately, they keep failing�aesthetically, anyway. This doesn�t bother classical music producers; they love (or at least view as a necessary evil) the ticket and CD sales that crossover music generates.

The word �crossover� is a red flag to the classical music purist. Not only does the flag snap in their face, but the flag pole pokes them in the gut, and the cast bronze eagle on top of the pole conks their cranium.

Most classical crossover projects fail miserably on aesthetic terms. Opera stars with wide vibratos and bad English diction can�t convincingly sing musical theater, and surrounding them with legit Broadway singers only heightens the incongruity. Classical instrumentalists who play note-for-note transcriptions of jazz solos usually fall short of the original in missing out on the unnotated subtleties of rhythm, phrasing, and timbre that a jazz musician instinctively supplies. Arranging a Metallica song for orchestra or a Beach Boys tune for string quartet is an unnatural act far more heinous than carrying an ounce of marijuana or offering sexual services for money; yet our hypocritical society allows these arrangers to walk the streets and corrupt our minors while we imprison potheads and prostitutes.