Barbershop quartet singing may not rock the house, but it can certainly make the air quiver when all four crooners hit perfect pitch and vibrato at the same time, says Mike Walsh.

Walsh, a 71-year-old Loganville church choir baritone, says the quartet bug bit him when he stumbled 12 years ago into a performance much like the one the Stone Mountain Chorus is hosting Friday and Saturday for its annual fall show.

He could not get the precise four-part harmony out of his mind.

“The quartet maximizes overtones and produces what we called expanded sound,” he said. “If you do it correctly, you end up getting a sound that sounds like five or six people singing. That will put chill bumps on your arms.”

When he got a chance a couple of years later, he joined a group. Now he helps pull together the fall show, which brings some of the best quartets in the country, including the 2010 national champions Storm Front, to the Gwinnett Performing Arts Center. The performance, offered on three times over two days, is put together and performed like an old-time radio show — think of A Prairie Home Companion—complete with commercials and a comedic drama.

The unique a cappella Amerian art form of barbership singing has been around since the 1800s and underwent a revival in the 1940s.

Performances are 8:30 p.m. Friday, and 3 and 8 p.m. Saturday. Tickets are $22 in advance or $18 for seniors and students, or $25 at the door. For more information call 770-978-8053 or go do www.stonemountainchorus.com on the Internet. the center is at 6400 Sugarloaf Parkway in Duluth.