Matthew Van Hoose, left, and Glenn Donnellan. (Courtesy of Glenn Donnellan)

Playing to an audience of about 30,000 people at least 82 times a year, Matthew Van Hoose may be the most heard musician in Washington.

Van Who?

Matthew Van Hoose is the generally unseen organist accompanying every Washington Nationals home game. Although the ballpark’s resident DJ may get more attention for blasting walk-up music or seventh-inning stretch anthems, it’s Van Hoose who plays organ renditions of pop songs, comments on plays and revs up the crowd with his keyboard.

But away from Nats Park, he’s Dr. Van Hoose — musician-in-residence at American University’s performing arts department. The classical pianist has performed with the Virginia Symphony Orchestra, the NIH Philharmonia, the Oberlin Conservatory of Music and members of the Baltimore Symphony Orchestra.

On May 9, Van Hoose will join forces with National Symphony Orchestra violinist Glenn Donnellan for “Beethoven at the Ballpark!,” two children’s concerts at the Kennedy Center Family Theater. He and Donnellan, known for his Electric Slugger fiddle made out of a baseball bat, will do what Van Hoose does all season: move from baseball to classical music and back.

After a recent Nats home stand, we talked to Van Hoose about his musical career.

When did you start playing for the Nationals?

I’ve been playing for them since the start of the 2010 season. So this would be the start of my sixth year. It’s a great job because I also became a big baseball fan as I was growing up, so it was neat to be able to do this. There’s a great tradition, obviously, with organ playing, not only in baseball, but hockey and basketball, so it’s fun to be part of that.

It seems as if recorded music is taking over a lot of games. Are there still a lot of organists?

I’d say right now, out of the 30 teams, only half use them. It’s too bad that more don’t have it, but it’s nice to connect with others that do have the same thing. . . . I think we’ve been having a nice mix at Nats Park of things I do, but also the DJ playing a lot of music that fits whatever we need. That’s what we both do: try to fit music to the moment.

Is there a lot of planning involved?

The first season, I wanted to go in with a plan and have a bunch of different things to be able to pull from at a moment’s notice because you never know what’s going to happen — if there’s a delay or whatnot, you might need to play something. But then after getting going, I’m pretty comfortable with either coming up with things on the fly or coming up with an idea.

Who makes the song choices?

Some of them are mine and some of them I coordinate with other people who are with the Nats, and we come up with some ideas. Not every night game, but once a home stand, you’ll hear “Tonight” from “West Side Story” if it’s a night game. Then you can throw in songs about the weather. If it’s a sunny day, “Here Comes the Sun,” or “Raindrops Keep Falling on My Head” for a rain delay. The really good one is “Heart” from “Damn Yankees,” just for its relation to the Washington Senators. That’s a song I’ll throw in when we’re trailing to try and say, “We can still win” kind of thing. In terms of other things, I’ll throw in some Duke Ellington every now and then, or I might decide to come up with a Maroon 5 or something, and come up with an organ version of that.

How do you and the DJ work?

We sit next to each other in an audio booth in the press box on same level where the TV and radio are. Sometimes they’ll ask us to play something specifically. But most of the time the DJ and I are working things out because we’re in the same room.

Do you have names for those little ditties that usually end up with “Charge!”?

We’ve come up with our own system for that. I would categorize all of them as rally prompts, if you will. We don’t name them. There are four or five different things that I try to rotate. . . . One of the ones we use is one I created that’s a chromatic passage that goes upward.

How did you get involved with this classical children’s concert?

I got to know Glenn Donnellan, since he does a lot of Electric Slugger anthems at the park. My boss had an idea one day of having us play together opening day last year. . . . We quickly became friends and also developed this fun musical connection. . . . He was the one who came up with the idea of doing these children’s concerts. I think what we’re going to be doing is showing the kids . . . how many things a musician can do. We might do some classical excerpts here and there, but then we’ll also segue into baseball-related things.

Which classical pieces have you found to be most effective for drawing in children?

Part of it is familiarity — something they heard in a cartoon or somewhere down the line. Typically with kids, it’s things that may be overplayed, whether it’s “Fur Elise” or the opening of the Beethoven Fifth Symphony. They’re obviously great works, but those can be something that a kid could be really familiar with. You try and catch their attention with that. But we’ll also be using anything with interesting rhythms. . . . What also tends to work is anything that works with contrast. We have a passage where there’s a sudden change from loud to soft or vice versa that can work.

Have you ever pulled out a classical piece during a game?

I did a little bit of that at NatsFest where I played some Bach. But usually during games, I just figure out something that’s connected with what’s going on, on the field. One classical tune that can work is something like an organ version of the “William Tell Overture” during a rally segment. But it’s something I generally need a little more time for.

Catlin is a freelance writer.

NSO Kinderclassics: Beethoven at the Ballpark! May 9 at 11 a.m. and 1:30 p.m. at the Kennedy Center, 2700 F St NW. $20. 202-467-4600. www.kennedy-center.org.