It’s a Saturday night and a friend and I are nestled in our seats at Ham Hall, absorbed by the third movement of Tchaikovsky’s “Fourth Symphony.” The audience is fully invested in the Las Vegas Philharmonic performance, with one movement still to enjoy. Then something crazy happens. Something I’d never experienced at a symphonic performance: Third movement ends. Clapping ensues, followed by shushing. Not just a little, but a multivoiced shhhhhhhhhing, mixing with, and then drowning out, the barely begun applause.

Had those who don’t clap had enough with those who do? Common theater etiquette dictates that clapping should be reserved for the end of the performance—not between movements. The Philharmonic used to advise this in its printed programs. Still, some audience members continue to clap during the pauses, while others remain quiet.

A couple of days later I call Philharmonic conductor David Itkin to hear his opinion. He answers his phone from inside a movie theater, which seems an affront to all theater etiquette, but explains that his family is the film’s only audience. “Neither one is right or wrong,” Itkin says regarding clapping. “It’s a question of where you’re sitting and what time you’re living in. [Not clapping] is a late-19th century, early-20th century phenomenon. Before that, not only did you clap between movements, if you clapped loud enough, they’d have to play it again. That’s what ‘encore’ meant. They’re saying, ‘I loved the piece so much I want you to do it again.’ I’m finding that general sensibility to be changing back.”

But, Itkin says, not everyone is happy with the clapping: “I’ve even had people call and email, asking, ‘Would you please address this from stage?’ But I’m not going to do something that people perceive as disciplining the audience. It doesn’t disturb the performance and our main job is not to teach manners. Our main job is to get people excited about music.”

So why Saturday night’s shushing smackdown? It turns out—my eyes were closed, so I missed this—that Itkin kept his arms in the air to connect the third and fourth movements without applause because, he says, at that moment, the music called for it.