LEWISTON – Battle of the Blends XV is coming Nov. 1.

Dozens of unaccompanied voices will join in everything from barbershop harmonies to pop/rock tunes and complex rhythms of the world’s folk songs.

Over the past 15 years, this fall fundraiser for the Maine Music Society has become the largest a cappella showcase in Northern New England.

This year’s performance takes place at 7:30 p.m. Saturday, Nov. 1, at the Franco-American Heritage Center.

Judith Andrucki, who has organized the event since its beginning, said she believes Battle of the Blends XV will be among the best ever presented.

“I think this is going to be a very interesting evening because of the diversity of the groups,” Andrucki said. “There are high-school students, college students, professional people and women who have been singing together for many years.”

The Battle of the Blends productions also have grown to become an important component of the Maine Music Society’s education mission, said Andrucki, who is current president of the MMS board of directors.

“We are delighted that many people are discovering the delights of a cappella performance,” she said.

Andrucki added that she is amazed when she thinks of all the singers who have appeared with groups in all the shows.

“Just imagine,” she said. “We have had six groups a year for 15 years.” Groups ranging from quartets to large choral ensembles add up to several hundred performers.

An eight-member group known as Hot Buttah is new to this year’s lineup, but its members are no strangers to Battles of the Blends. Hot Buttah was formed when two Maine a cappella groups, Referendum and ImproVox, combined to bring beautiful four-part harmonies and rich improvisational flavors to a variety of musical influences.

The group’s promotional material states that members sing “with skill and abandon and a zesty enthusiasm for life and music. We are not afraid to break the rules.”

Another new group at Battle of the Blends XV is Manic Optimists. Formed in 2000, it is Bates College’s newest all-male a cappella group. Singing primarily contemporary pop/rock songs, the ManOps are known for their high-energy and engaging performances.

Andrucki said they are “excellent and really well-traveled.”

The Royal River Chorus is one of the larger groups scheduled to perform. It is a chapter of Sweet Adelines International, the world’s largest music education association for women singers, and it was chartered in Yarmouth in 1983 by 12 experienced Sweet Adelines.

Throughout the years, Royal River members have maintained a bond of friendship in harmony, and they eagerly welcome other women to share their hobby.

In recent years, the 25-member chorus has maintained standings within the top five at the annual Region One Competition in Springfield, Mass.

Under the direction of Robert Russell, conductor, the University of Southern Maine Chamber Singers also will appear at this concert.

Throughout the northern New England region, the Chamber Singers has performed a diverse repertoire centered on a cappella literature of the Renaissance era and the 20th century and music of various world cultures. The ensemble has toured in Europe several times in recent years. Last May, members toured Prague, Vienna, Slovakia, Auschwitz, and Krakow.

Zemya is a nine-woman a cappella vocal group based in Topsham. They perform a wide range of folk music from around the world sung in the native languages. Its current repertoire includes songs from the Balkans, South Africa, Israel, Ireland, Bulgaria, Romania, Croatia, and the Americas.

The group takes its name from “zemya,” the Bulgarian word for earth and soil.

Mt. Blue Voices is a group that has its roots in 1995 when members of Mt. Blue High School chorus students approached their director, Dennis Hayes, and asked if he would be willing to start up an auditioned vocal ensemble that would challenge interested singers in a unique and entertaining way. Since then, The Voices have become one of Maine’s premier high-school vocal groups and has appeared at Battle of the Blends performances twice before.

The 15 members of The Voices sing in the contemporary a cappella style found on college campuses across the country. They perform personalized arrangements done for the group by Hayes, which highlight the individual strengths of the student singers.