BIRCH HOLLOW, Minnesota — Birch Hollow Public Schools will hold its fall instrumental recital in the high school gymnasium after applause from an empty auditorium repeatedly interrupted a student rehearsal. The clapping caused no injuries, but instructors said it began before several pieces had ended and made it difficult for performers to keep time.
The first interruption came Thursday afternoon as junior violinist Naomi Kroll played the final measures of a Bach partita for music director Elise Morrow. Custodian Dan Rusk had locked the two lobby doors, and the 286 seats were unoccupied. About 20 seconds before Kroll reached the written ending, applause rose from the rear rows and moved toward the stage in what Morrow described as an ordinary audience pattern.
Kroll stopped, believing someone had entered. The sound stopped as well. When she resumed three measures earlier, the applause returned at the same point in the score, this time joined by several isolated claps near the front aisle. Morrow walked through the room while Kroll played a third time and found no phones, speakers or people beneath the seats.
A brass quartet rehearsed Friday morning with similar results. The clapping started during a sustained final chord, before the conductor lowered his hands, and continued for six seconds after the players stopped. It was not especially loud, students said, but it had the uneven quality of separate hands rather than a recording. One student heard a cough between two bursts of applause.
Principal Carol Lund closed the auditorium Friday afternoon and moved rehearsals to the band room. She said the decision was made because performers had begun shortening rests and rushing final passages in anticipation of the sound. The recital will proceed Monday at 7 p.m. in the gym, where folding chairs and portable acoustic panels will be installed.
District technology staff disconnected the auditorium sound rack and removed a wireless microphone receiver that had occasionally picked up taxi radio traffic. The applause continued during an unamplified piano exercise after the circuit breaker serving the stage outlets was shut off. A recording made from the aisle captured the clapping, though a second recorder placed onstage registered only the piano.
Sound can travel unpredictably through an auditorium, particularly along heating ducts and beneath raked seating, said Soren Pike, an acoustical consultant who reviewed the recordings for the district. Gym activity, construction and even repeated impacts in a nearby mechanical room can resemble applause. Pike said those sources would not normally adjust their timing when a musician paused or repeated a passage.
Morrow tested that timing Saturday with a metronome and a marked score, asking two teachers to observe from the lobby windows. During a student performance of a three-minute clarinet piece, applause began at the start of a difficult run 14 measures from the end. The student missed a note, returned to the beginning of the run and played it cleanly. The room waited through the correction, then applauded again seven measures later.
Students have not been asked to reproduce the condition, Lund said. The district postponed Sunday access for a community theater group and will inspect the ductwork, seat frames and old assistive-listening loop. Ticket proceeds from Monday's recital will still support instrument repairs, and families who cannot use the gym's bleachers will be given floor seating.
Rusk entered the auditorium alone Sunday morning to collect programs left along the back row. He said the room remained quiet while he crossed the aisle and gathered the papers. As he stacked them, he noticed that the printed running order had been rearranged on four programs in the same way: Kroll's solo appeared last, although the school office had printed it fifth.
The auditorium doors were relocked at 10:15 a.m. Before leaving, Rusk placed one straight-backed chair at center stage so inspectors would have somewhere to set their equipment. The empty seats applauded for nine seconds. The chair remained where he put it, facing them.