The Society for the Preservation and Advancement of the Harmonica and its national convention is in Tulsa this week.
They call it the world's biggest harmonica party.
Everywhere you look there's people playing a harmonica of one kind or other.
Like Joe Filisko.
He's a music educator, and historian of the harmonica and its musical styles.
He said they've been around since the 1820s. They're portable and can produce a big sound if they need to, like a train.
Michael D'Eath is the national organization president and he says the harmonica is a special kind of instrument different than any other.
"With a harmonica you breath through it ... so it's very much a part of your soul," D'Eath said.
People play jazz, country, classical, all of it, out a relatively small instrument.
In the vendors area there are harmonicas everywhere. From plain ones to fancy ones, big ones and small ones. And everybody plays.
There's even harmonica jewelry.
Blues is where harmonicas really shine. Playing blues.
The event will be held at the Hyatt Regency Hotel, 100 East 2nd Street.
There are evening concerts and jam sessions.
Friday and Saturday there are special programs for kids.
You can find out all about it at www.spah.org.