On a subfreezing night with an untested concert format, is it any surprise that the Philadelphia Orchestra's first LiveNote Night, designed to attract new audiences to classical music, was preaching to the semi-converted on Wednesday at the Kimmel Center?

The event represented a confluence of past seasons' "Beyond the Score" concerts (earlier, shorter, instructively oriented) and the pop-up performance scheduled spontaneously in 2013 when the orchestra's Carnegie Hall date was canceled by a stagehands strike.

The centerpiece of Wednesday's concert, though, was the LiveNote app, developed in collaboration with Drexel University over several years, which gave running commentary on the music's structure and content, available for use during the performance. At a time when most orchestras are policing interruptive phones during concerts - in China, red lasers zap offending users - here smartphones were not only kept on but encouraged, though the specially designed darkened screens created by the app are theoretically not distracting to nearby patrons, and repeated messages appear on phone screens reminding everybody to turn down the ringtones.

The app offered two kinds of guidance: Program notes by Benjamin K. Roe about the process of the symphony's composition, and a graph of sorts that showed the symphony's structural points and at what point the performance was in any moment. Trial runs at past concerts had about 18 percent accessing the information, according to orchestra spokespeople.

The usual gray heads at orchestra concerts were mixed in with student-age patrons who could afford the $45 tickets, in a crowd of about 600 that allowed listeners to hear what the orchestra sounds like when Verizon Hall has fewer sound-absorbing bodies.

The audience was seasoned enough in classical music that no clapping was heard between movements of Tchaikovsky's Symphony No. 5, led by music director Yannick Nézet-Séguin. And that was the concert's unquestioned success. Though the conductor was the format's best advocate, with his friendly, conversational manner, listeners reported that his performance was so absorbing that they stopped using the app.

Among the 50-somethings was Diane Cloutier of University City, who thought the app was "well done," though she didn't get beyond the first screen's running commentary. Her concert companion, Kaye Baluarte of Mount Airy, was more engaged: "I didn't know the story behind the music, with his loves and sexuality. It made it more interesting."

A group of students from West Chester and Temple Universities was similarly mixed. Some admitted that they preferred auditing the commentary by peeking at the phones of their neighbors.

The concert's prelude, however, had the audience divided along the age line. A prerecorded video interview had Nézet-Séguin sparring with online personalities Nicholas Canellakis and Michael Brown, who specialized in humor based on their supposed cluelessness (though they're said to be quite intelligent). They spent most of the time learning to pronounce Nézet-Séguin's name and getting it ever more wrong. Some thought it funny. For Baluarte, "It was ghastly."

To me, it was irrelevant. Being in the room with such a conversation is a different experience than sitting in a theater experiencing it on video while waiting for the performance to start. Also, irrelevance in the classical world is more out of place than, perhaps, in popular culture. The point of classical music is distilled expression that has survived for centuries and continues to speak to audiences, transcending fashions and trends. Even the longest symphonies have the impact of a far-longer epic film. To precede the vital and lean narrative of Symphony No. 5 with irrelevance can't help but dull one's sense of anticipation.

No doubt the format will be refined in subsequent LiveNote Nights, Feb. 25 and April 22 - the earlier program featuring Jennifer Higdon's fairly recent Violin Concerto. So the core content is highly substantial - which is what is, for lack of better words, deeply relevant.