It may be a truism that classical music tells its story on a canvas of silence, but this simple idea takes on an edge of peril for any parent or caregiver to someone with autism, Tourette's, or any number of other afflictions. For them, the concert hall is a place of tenterhooks and dueling impulses. You want the person in your company to experience the art, but — painfully aware that an aural or physical disruption can come at any moment — you also keep one eye on the exit.

No worries, the Philadelphia Orchestra declared Thursday with what was billed as its first sensory-friendly full-orchestra concert.

Verizon Hall was moderately filled with special-needs children and adults. The news that the evening would be "shush-free," as orchestra president Allison Vulgamore put it, settled like a balm over an audience perhaps wearied by the daily task of translating between a highly individualized population and a world that doesn't necessarily speak their language.

For years, my seats at the Philadelphia Orchestra's Saturday morning family concerts were behind a woman who spent much of the hour managing a son who periodically writhed and verbalized loudly. I can't speak for others, but her persistence won my heart. What was so liberating about Thursday's concert was that no one had to explain anything to anyone. My own seatmate Thursday lives with intractable epilepsy, autism, and a highly selective range of intellectual peaks and valleys. He can't understand how a map represents the world, and once asked who turned off the waves at the beach each night. He also happens to be very much the music critic's brother, which means he easily identified with the Mozart (the first movement of Eine kleine Nachtmusik) and just about everything else the orchestra played.

Many others also looked rapt by the hour-long concert, and in a variety of ways. What was sensory-friendly about the program? Actually, the concert was more about adjusting the behavior of the staff and everything around the music than the repertoire itself. Patrons were told they could move around and talk. House lights were kept up. "Cool-down" spaces were created in the lobby. A complement of ushers, Temple University students, and helpers from Art-Reach stood at the ready with special assistance.

Orchestra composer-in-residence Hannibal Lokumbe created a new piece for the occasion. Hymn for the World charmed as a proud, marchlike procession of beating and glistening percussion. Hannibal always catches humanity at its best. Tan Dun's alternately menacing and sensuous Passacaglia: Secret of Wind and Birds turned audience into performers by having them download a sound clip of birds to their cellphones and playing it on cue. The "Hoe-Down" from Copland's Rodeo and Strauss' "Radetzky" March were occasions for listeners to wave the ribbon-tipped batons they had made earlier in the lobby.

"Now you've officially performed with the Philadelphia Orchestra," conductor Kensho Watanabe told the audience.

He might not have known the half of it. When he turned his back for the encore, "Stars and Stripes Forever," one boy in the middle of the hall stood up, air-conducted with his plastic ice cream cone, and vocalized at the top of his lungs. The music seemed to fill every inch of his body, and anyone who didn't hear his song as a moment of absolute harmony was simply missing the point.

There are no additional performances of this concert; the orchestra will evaluate the format and consider future full-orchestra sensory-friendly concerts. The orchestra, however, does offer sensory-friendly experiences for some of its Sound All Around concerts with smaller instrumental forces., 215-893-1999.