BANGOR – A Four Shillings Short concert is a musical smorgasbord, offering traditional Irish tunes and airs, Indian ragas, folk ballads, medieval and Renaissance instrumental and a cappella numbers, contemporary folk and original compositions.

The husband-and-wife team of Aodh Og O’Tuama and Christy Martin perform these on a variety of the 20 instruments they play. The peace and environmental activists also will mix in some global politics as well.

The duo, who will play at 7:30 p.m. Saturday at the Brick Church in Bangor to benefit community radio station WERU, are modern-day troubadours, traveling the country in an aging van holding their instruments, a cell phone and a laptop and staying with people along the way.

“Musicians play a very singular role in society,” Martin said. “We have been in communities across the U.S., and talked to so many people. We stay in communities with families and connect with them, to see what their concerns are. When we open our mouths, we talk about what we’re learning across the country, about U.S. foreign policy, about the gap between rich and poor, about the lack of support for education. We address the concerns we hear everywhere, and let people know that their concerns are everyone’s concerns, that they’re not alone.”

On this recent day, they’ve just come from Bangor International Airport. It’s not where they arrived in Bangor; rather it’s where they have been protesting against the potential war with Iraq during President Bush’s visit. At 1:30 p.m. Saturday, they’ll perform at the Peace Action Maine rally at the State Capitol in Augusta, along with supplying the sound system for the event.

Owning only their instruments, their vehicle and their clothes, the couple sees what they’re doing as service.

“We’re stimulating conversation, supporting people at a time when they’re frightened and don’t feel they have a voice,” Martin said.

“It empowers them to get a little more active, a little more vocal,” added O’Tuama.

Both members of Four Shillings Short, whose name comes from a James Joyce story about a musician who gets shortchanged, are from artistic families. Hailing from Cork, Ireland, O’Tuama comes from a family of poets, writers, musicians and teachers. He studied music at University College Cork in Ireland and Stanford University in California. Californian Martin grew up in a family of musicians and dancers and began studying the sitar at age 16 with a protege of sitar master Ravi Shankar.

O’Tuama co-founded the group in 1985, and it’s had many personnel changes through the years. Martin joined in 1995, and the couple has been the core of the group since then. They’ve recorded four albums together, most recently this year’s “Of Labour and Love.”

When choosing a song, the duo has to agree on it.

“Because we approach a song from so many different disciplines and styles, it has to be a little out of the ordinary for us,” Martin said. “A well-developed melody line is very important to us. We’re attracted to melodies that are intricate and interesting.”

When arranging a song, they try to make unlikely musical combinations, such as a mandolin paired with a Renaissance krumhorn, a bent horn with a double reed.

“We’re one of the few bands that doesn’t have guitar,” O’Tuama said. “We glory in the fact that we can do anything we want. We try to keep the music interesting to ourselves, and we think that keeps it interesting for the listener.”

With so many instruments to choose from, each song has to be designed carefully.

“We pick a song, then ask, ‘What chordal instrument does this work with? What key, what voice is it going to be in?,’ Martin said. “Then we narrow it down further. Who’s going to sing it? What instruments is Aodh Og going to play? A lot of it is crafting the various parts, especially when we’re marrying together two to three pieces of music.”

Lyrics are another key consideration.

“The poetry of words is very important to us,” Martin said. “The words have to be well chosen, the rhyme not what you would expect the typical rhyme to be.”

Musical preservationists, the couple believes that many old songs still speak to today’s audiences.

“There are parallels between today and the past,” Martin said. “It may be an old song, but its message is universal; it’s as relevant today as it was then. Music bridges, in a person’s mind, the continuity of history.”

They split their year between Ireland and the United States. They perform at folk and Irish music festivals, outdoor concerts, concert series, bookstores, schools, libraries and coffeehouses.

Their benefit concert came out of a request from Denis Howard, WERU’s development director. The couple is doing it because community radio stations are near and dear to their hearts, since those are the type of stations most likely to play their music on the air.

“We look to support community-supported radio as much as possible,” O’Tuama said. “There’s real music being played there, instead of the synthetic music you hear on mainstream radio.”

These two gypsy musicians will continue with their dual mission of entertaining and informing, hoping to get people to look at the bigger picture.

“We’re part of a global village,” O’Tuama said. “We all have common threads.”

For more information about or ticket to the Four Shillings Short concert, with opening act SoNiA, call 469-6600. For more information about the Peace Action Maine rally, call 772-0680 or 326-9574.