The humming rose from Hedgerow Theatre’s audience, from Colin Pryor, 21. Two actors on stage argued and as their dialogue grew heated, Pryor twisted in his chair, flapped his arms, covered eyes and ears with his fingers, then clasped his father’s hand, bouncing it in his lap.

Usually during a performance, the noise and motions might have been a distraction. But none of that mattered Sunday in the no-shush, no-judgment world at Hedgerow Theatre’s “relaxed and audio-described” performance of its show, Cowboy Versus Samurai.

“People experience the world differently,” said Marcie Bramucci, Hedgerow Theatre’s executive artistic director, who invited Sunday’s audience to be its “fullest self. Vocalizing and moving are welcome for you to enjoy as you like.”

When it comes to accessibility, wheelchair ramps, widened doors, and curb cuts come to mind, but there are other types of accommodation required for people like Pryor, a young man with autism, or for those with other neurological issues, such as dementia, agoraphobia, or post-traumatic stress disorder.

More and more arts venues are figuring out how to welcome this audience.

Veronica Chapman-Smith, for example, vice president of community initiative at Opera Philadelphia, attended the Hedgerow performance to apply lessons learned to operas in the spring. “It’s the right thing to do,” she said.

For arts professionals like Chapman-Smith and Bramucci, neuro-accessibility is an issue of equity and of audience development.

“It’s how we shift the culture of our organization to be more inclusive,” Bramucci said.

To do so, arts groups have tapped the expertise of Roger Ideishi, formerly a professor of occupational therapy at Temple University, who now commutes to George Washington University in D.C. from his home in Northern Liberties.

Ideishi has worked with venues in Washington, D.C., Minneapolis, Houston, and Pittsburgh, as well as globally in Dublin and Moscow, to make their spaces welcoming to people who are easily overstimulated, who need extra stimulation, or who find the dark frightening or the noises loud.

“It has really taught me a lot more empathy,” Ideishi said. “Now I see the discrimination the disability community experiences on a daily basis — and I won’t say daily, I’ll say on an hourly basis. Personally, it has transformed me.”

So, what constitutes a relaxed or sensory-friendly performance?

For Cowboy Versus Samurai, it started before the show. Hedgerow emailed ticketholders an 11-page guide describing characters and plot, as well as any scenes involving sudden noises: “Some moments in the play can be loud, [like] when the character of Chester bangs a gavel to begin a meeting.”

Before the first act, Bramucci invited the audience to the edge of the stage for “a sensory tour.” Attendees can meet cast members and touch props — a suede cowboy hat, a railroad spike, a bird cage. Bramucci banged the gavel on the stage.

It helps to know what to expect.

The 110-seat Hedgerow Theater, in Rose Valley, lends sound-canceling headphones and fidgets, small moveable objects fingered to alleviate anxiety. Hedgerow also hired an audio describer, who whispers what’s happening on stage through an earpiece for low-vision audience members. Some theaters offer captioning.

Hedgerow’s house lights remained on, but dimmed, so people could move or leave when they wished and return when ready. Calming zones in the lobby provided a refuge. No risk. If it doesn’t work out, Hedgerow offered full refunds.

Most important: Noises, flapping arms, walking, stomping feet — all are fine. “They get to be who they are,” Ideishi said.

“Sometimes the sensory stimulation is too much — too much noise, too many crowds,” Ideishi explained. “What would you do if you were standing next to a loudspeaker at a concert? You’d try to get away from it. You’d cover your ears or talk louder. If you didn’t have appropriate strategies, you might cry. You might scream.”

In the late 1990s and early 2000s, Ideishi was working with KenCrest to find more ways to integrate its clients — people with autism — into the community, from the arts to the supermarket. Early on, the Walnut Street Theatre, the New Jersey State Aquarium (now Adventure Aquarium), McCarter Theatre Center, and the Pennsylvania (now Philadelphia) Ballet developed programming.

Word got out and soon Ideishi was consulting with art venues around the world. When the John F. Kennedy Center for the Performing Arts in Washington became fully committed, other institutions followed. “Broadway was picking up a lot of steam and because Broadway was doing it, there was more direct marketing to the neurodiverse community,” Ideishi said.

Pittsburgh went all-in, with nearly every institution adding programming. That didn’t sit well in Philadelphia, Ideishi said. The competitiveness between the two cities helped ldeishi and Art-Reach, a Philadelphia nonprofit dedicated to connecting the disability community and low-income people to the arts, advocate for similar programming here.

In 2013, two actors with People’s Light attended a seminar at Art-Reach and came back inspired to start programming for neurodiverse audiences. One was Peter Pryor, Colin’s father. Shortly after, Bramucci, then newly hired as People’s community outreach director, took up the initiative — and soon, with Ideishi and Art-Reach, built People’s program and worked with other regional theaters.

“You see it growing. It’s really encouraging to see places embracing it,” said John Orr, Art-Reach’s executive director. He now describes Philadelphia as a leader. “This can rewrite the book on what arts interaction looks like.”

Actors, who often draw energy and inspiration from the audience, need to learn how to respond to a different type of reaction. The lights are on, so nothing is hidden.

“You concentrate on your performance,” said Pryor, who now teaches theater at Pathway School, a nonprofit special education school. “But if all you are is worried about is your performance, you are kind of missing the point. There’s real live communication with people in the house. The freedom is electric, and it goes back and forth.”

For both Leigh Dale, coordinator of family programs at the Philadelphia Museum of Art, and Sarah Cooper, creative director of community engagement and public programs for the Philadelphia (formerly Pennsylvania) Ballet Co., a joy of offering sensory-based programming is seeing families experience the arts together.

“You see families that are so excited to be at the theater,” Cooper said. “Once we started doing this, it became everybody’s favorite activity.”

On a business level, family appeal can build audiences, Bramucci said. Instead of two tickets, a family might buy four. But it takes trust. People’s, for example, developed its program after intensive interviews.

Another plus? Donors are often willing to underwrite these performances.

But there’s more, and it explains why Theatre Horizon, for example, is planning to include relaxed performances next season.

“Honestly, the neurodiverse population is a marginalized community that is really under-recognized in this moment,” said the Norristown theater’s artistic director, Nell Bang-Jensen. “When there’s a lot of attention on inclusion and diversity, people who are neurodiverse need to be part of those conversations as well.”

Please check individual venues for relaxed or sensory-sensitive performances. Here are a few upcoming events: “Swan Lake” at the Philadelphia Ballet, auditory description only, March 11, 2 p.m.; “Personality: The Lloyd Price Musical” at People’s Light March 20.