On a lazy Sunday afternoon in Aspen July 30th, Conductor Leonard Slatkin faced his unsuspecting audience and issued a warning: "Gorgon is unlike any piece you've ever heard ... concentrated energy in its rawest form ... the Rite of Spring on steroids ... evil and horrible ... evil incarnate." To put it simply, Gorgon is loud. Very loud. So loud that David Zinman, who premiered the work in Rochester in 1984, recalled: "Of all the pieces I've conducted, that was the most damaging. I remember coming off the stage afterward - your hearing shuts down, protecting you when the decibel level is so high. I was completely shattered afterward, completely shattered. I had the feeling that my eyeballs were going around in circles." This piece - or, I should say, phenomenon - is not written for electronic instruments. It's composed for a fairly large acoustic symphony orchestra and, well, 73 percussion instruments (56 different types), including all kinds of bells, gongs, drums, and - dwarfing the rest - three plywood boxes, specially reinforced by Aspen Chamber Orchestra Principal Percussionist Jonathan Haas to be bashed with iron pipes. Christopher Rouse, a regular at the festival - he now heads the Susan and Ford Schumann Center for Composition Studies here - is the man responsible for composing this musical mayhem. As Slatkin explained to the assembled audience-victims, "Chris wants you to be disturbed by this. Rhythmic intensity and sonic density are what to listen to." In other words, not the normal features of classical music like melody and harmony. What Rouse has in mind is to terrify. As he put it back in 1984: "Since the time of the ancient Greeks, the Gorgon has been a symbol for any terror too immense - and too horrible - to be faced. It has thus become an image of sublimated brutality and savagery, perhaps a metaphor for our own private and subconscious monsters." There were three mythical Gorgon sisters: Stheno, Euryale, and most famously, Medusa. A single glance from any of these snake-haired, tusk-toothed babes would turn anyone to stone, a fate that the hero Perseus evaded in Medusa's case by using his shield as a mirror to guide his lethal sword thrusts. Rouse sets all three of the sisters in his 18-minute assault on the senses. The three movements, one per sister, are separated by two interludes (Perseus Spells) for percussion only. All five sections are played without pause and rip along uniformly at 176 beats to the minute. Needless to say, this is not your everyday serenade. As devastatingly thrilling as it is, Gorgon is exceedingly difficult to play and rarely performed. Many musicians make careful notations on their scores indicating where to insert earplugs and they practice (and practice) playing rapid-fire notes all over the map. Despite the rarity of performance and his earlier involvement at Aspen this summer, Rouse was not able to attend (he was vacationing in Florida). No problem, Slatkin assured the audience, "It's so loud he'll still be able to hear it even there!" Even after Slatkin's warnings, however, the woman next to me yelped involuntarily and covered her ears as triple-forte trombones, tuba, cymbals, gong, and the rest of the orchestra, began the Stheno movement with a machine-gun DA-da-da-da-da-da on a dissonant A note against B flat, building up in 30 quick bars to a shriek-shriek-shriek-shriek-shriek-shriek BANG-duh, the final notes of that hair-raising phrase bashed out on timpani, slapstick, and brake drums. Of course, loud is a relative term. The genius in Rouse's Gorgon is that there are plenty of weirdly quiet passages to set up the barrages. Ironically, the middle movement, Euryale, after the Gorgon noted for her bellowing by the ancients, is the least noisy. Instead, flesh-crawling, trilled glissandos in contrary motion inhabit the strings. The second Perseus Spell, scored for vibraphone, marimba, xylophone, and glockenspiel, is also subdued. Not so the first Perseus Spell, which explodes forth quadruple forte with bass drum, timbale (a kind of kettledrum), tom-tom, and timpani (BOMB BOMB BOMB BOMB BOMB BOMB). By this point I'm sure many listeners wished the program had come with aspirin tablets. But taking them would have been useless against the might of Medusa, which starts off as the louder Stheno and builds to an overwhelming onslaught with the addition off shock-and-awe weapons - namely, ratchets, chimes, gongs, metal plates, and the aforementioned three boxes - to end con tutta forza possibile, quintuple forte. The audience loved it, but their standing ovation and whistles managed only a pianissimo compared to what provoked their gratitude. Gorgon was preceded by an opposite, Mozart's inconsequential F-Major concerto for two pianos, K. 242, played charmingly by two fine musicians barely into their teens, Peng Peng and Conrad Tao. To great acclaim, the pair followed with an encore, composed by the latter, of variations on Happy Birthday, played for David Zinman, who beamed from the back row. After an imperative post-Gorgon intermission, Slatkin and the orchestra returned to perform Tchaikovsky's Fifth Symphony. But nature, roused by a human upstart, decided that anything Rouse can do, it can do louder. A gargantuan thunderstorm, perhaps heard beyond Florida, pelted the Benedict Music Tent without mercy. Tchaikovsky, no stranger to multiple fortes, became barely audible in the tempestuous first movement. Now the audience was treated to a unique spectacle. Drowned out by the storm, Slatkin - a man whose interpretation of the symphony in rehearsal earlier that day left local experts praising its historic importance - was left helpless. There was no way he could start the famous, gently romantic second movement. After a few minutes, he sat down on his podium like an old man on a curb waiting for an overdue bus. Finally, he rose and walked offstage. He was back in a few moments with a microphone, proposing that the louder finale be played next, followed by a return to the middle movements should the storm abate. The audience agreed with loud applause. Amid thunderbolts and the pelting of the tent shell from above, hints emerged of what might have been. Slatkin's idiosyncratic use of rubato added power and feeling to crucial passages. Alas, the storm did not let up. The wild cheers of the crowd were not sufficient to justify waiting another half hour for the storm to subside. Slatkin did not return, the crowd mingled with the musicians or lingered near the exits watching the deluge, and the concert was over. Gorgon is an amazing composition that must be heard to be believed. Something incredible happens every time it is performed. That's why I've been in attendance at its last four venues - Santa Cruz, Denver, Winnipeg, and Aspen - and I will go to the ends of the earth to experience it again. Jeff Dunn [log in to unmask] Alameda, CA