When Ronan Mattin exclaimed “wow!” at a Handel and Haydn Society concert last May, he not only broke through the silence between movements, he inspired others to break convention as applause erupted through the crowd.

Ronan is on the autism spectrum, and is usually non-verbal. Yet with one word, the 9-year-old New Hampshire boy charmed a whole concert hall, and sparked a search for the “wow kid” captured in an audio recording from WCRB-FM, Boston's classical radio station (and part of the WGBH Foundation).

Mattin’s grandmother, Claire Mattin, saw the request on a news report, and soon a Skype chat was arranged for Ronan and Harry Christophers, the conductor of that concert.

Six months later, Ronan and Christophers got the chance to meet in real life, during a rehearsal Thursday at Symphony Hall ahead of opening night for the Handel and Haydn society.

"It makes us as musicians just feel incredibly humbled, but also delightful about what we do,” Christophers said, “because we know there are these fantastic reactions. And Ronan's was so lovely, so spontaneous."

Though anything but absolute silence is often frowned upon between movements, Christophers said Mattin’s reaction had the power to make the entire performance feel more accessible and more human.

“The concert hall sometimes in a very sort of … overpowering,” Christophers said. “And actually to have this moment where Ronan just instantaneously has this reaction, which was just fabulous.

“This is often the trouble with the perception of classical music,” Christophers continued, “but actually it touches everybody's heart whether it be young or old.”

Even at their meeting, Mattin eluded convention, turning his small body to rest his head on Christophers’ knee, before running down the hall to inspect the building’s elevators.

At one point, Mattin burst through two double doors into a room where Toby Oft, the principal trombone of the Boston Symphony Orchestra, was practicing.

Oft let Mattin touch the base of his trombone while he played. “Do you feel the vibrations?” Oft asked. Mattin nodded.

Like everyone else who meets Mattin, Oft was charmed, as he was the first time he heard “wow!” uttered last year.

“I think a lot of times people go to the symphony, and they try to contain themselves and sit still, like maybe the way you felt when you were a kid and you were told to be seen and not heard,” Oft said. “The idea that you would go to a concert and participate is something that we need to make space for.”

While musicians rehearsed Mozart on stage, Mattin kicked his feet on the floor, sometimes singing a high note along with the soloist. His eyes, usually cast to the floor, remained fixated on the stage, as he sat between grandmother Claire and grandfather Stephen Mattin.

"He really feels it inside, and I think that one little word, ‘wow,’ makes other people stop and listen and say, 'Oh yeah! This is good,'” Claire Mattin said.

As Claire Mattin watched Ronan watch the music, she began to tear up.

“We're so proud of him. He is just such a special guy,” she said. “It gives you chills. … His love of the music is contagious.”

Correction: An earlier version of this story incorrectly stated the amount of time that has passed between the concert Mattin attended and his meeting with Harry Christophers.

Correction: An earlier version of this story incorrectly spelled the names of Claire and Stephen Mattin.