They have been a part of every performance at the Sweet Thunder Festival, heard but unseen. Equal parts hecklers, revelers, and performers, they are the persistent seagulls perched atop the Festival Pavilion at Fort Mason. During Saturday evening’s concert in San Francisco they seemed especially prevalent. During Poème électronique, they muttered in the background as if a part of Varèse’s soundscape. If a passage of explosive dissonance subsided into a murmur, the seagulls would reliably fill the quiet with a chorus of squawks — loud enough to be heard but quiet enough not to be disruptive. It was a reminder that Varèse intended the piece to be a living work. While a step up from listening to it on a recording, hearing Poème électronique in a concert setting is far from the immersive experience of hundreds of loudspeakers in an exhibition space that the composer originally designed it for. Both it and Déserts, the concluding piece on the program, will always be important landmarks in the electroacoustic canon, but contemporary performances make them feel like museum pieces.  

Varèse’s vision and the sounds he created are remarkable for their time, but today both are showing their age. While the scratchy harshness of the audio tracks retains its radical edge in a way conventional atonality has not, the pervasive distortion gives it an almost quaint patina. In Déserts, Varèse envisioned a face-off between electronics and the ensemble. But the face-off never escalates into a skirmish, with the extended forces of the San Francisco Contemporary Music Players and the loudspeakers politely taking turns blasting their raucous melodies of shifting timbre. SFCMP artistic director Steven Schick noted before the performance that Déserts is what inspired him to devote his life to music, and it showed. Even if the piece is a bit dated, it was given a masterful performance that reminds us just why it will remain a warhorse of electroacoustic music.

Another of the genre’s landmarks, Kaija Saariaho’s IO also has the feel of a relic. With so many performed during the festival being driven by live electronics, the use of a static audio part makes IO seem static, since the ensemble must always tailor itself to something that is always exactly the same. Ashley Fure’s Albatross attempts to address this. While still utilizing a pre-recorded audio part, the samples were gathered from live recordings of performers that are meant to inspire the audience to pay closer attention to the people onstage rather than the electronics. In part, this succeeded. But at times the sounds of shuffling feet and swishing skin resembled a great vessel crashing through stormy seas to the point, something reinforced by the choreographed swaying of the performers. When the entire chamber orchestra suddenly stopped and stared at the ceiling, thoughts inevitable turned toward the seagulls just a few feet above.

Also using a pre-recorded tape part, but in a very different way, was Mario Davidovsky’s Synchronisms no. 10, for solo guitar. In contrast to IO or Déserts, the purpose of the electronics is to blend seamlessly with the instrument, performed by the indomitable champion of new guitar music, David Tanenbaum. Several minutes pass before a single electronic beep, and when the audio part enters, it seems to spawn from the guitar itself. Despite being permanently fixed, the effect is remarkably fluid.

Singer, composer, and playful tinkerer Pamela Z easily delivered the strongest performance of the concert. Her solo work Unknown Person infused a touch of absurdity — building a song from a question a passenger might be asked at the airport — into a masterful example of technological wizardry and vocal agility. Both Unknown Person and (v)erstählen liberally layered loops of the composers live vocals to create otherworldly textures. Then, waving her hands in the air in front of a glowing device perched next to her, she manipulated the sound in a way that is obvious in its effect but mysterious in its execution.

The seagulls were impressed. As Pamela Z and Steven Schick wound down their performance of (v)erstählen, they exploded into an uproar of cheers. As the music faded into tranquil silence, both performers strained to keep a straight face. Eventually they gave in, and laughed. The audience joined them, and then joined the seagulls with enthusiastic applause.