Euphonium.

Music The Houston Chronicle interviews euphonium player Matt Stephens, who's been selected to join the band for Macy's Thanksgiving Parade in New York City:

"Stephens said he practices a hour or more each day. He joined band when he was in sixth grade.
"I was just a music person," he said. "Band was what I wanted to do."
He said he tried playing several instruments, but not one felt right until he picked up the euphonium.
"It just fit me," Stephens said.
He plans on playing the instrument for life - even though he said he will major in accounting or finance in college. He hopes to attend Sam Houston State University next year.
When he is not in school, Stephens works in a bowling alley and also bowls competitively.
"I spend most of my time aside from the band hall at the bowling alley," he said. "I just like to bowl."
But music is what drives him.
"If I'm ever feeling down, I just pick up an instrument and start playing," Stephens said."

YouTube has plenty of videos of Matt and the rest of the band in action.