Tim Eriksen used to play in some Boston-based modern-rock bands, as most collegiate Beantown types do. But one day he discovered shape-note singing, and nothing’s been the same. A veteran of the Cold Mountain soundtrack and an expert in folk violin, Eriksen’s musical repertoire consists mostly of 19th-century American ballads and tearful yarns, mostly of the Civil War variety. His old band opened for Nirvana in the ’90s, but earlier this decade he warmed up for another Albini friend, Nina Nastasia, at Old Town School Of Folk Music. Soul Of The January Hills, his most recent effort, makes full use of his voice as an instrument, which is fortuitous: it’s the only instrument on the record. (Friday@Old Town School with Bob Mould.)

Let’s hesitate before we pronounce apartheid en vogue, though the presence of the World Cup in South Africa, Strut’s Next Stop Soweto compilations, and the Invictus film (Cinemax even ran A Dry White Season on cable this summer) certainly are making its presence felt. Trumpeter Hugh Masekela lived the repression not vicariously through sport or the arts, but as a subject of the regime. A daring archbishop encouraged Masekela’s musical education and eventually planned his defection to London, but — much the same way American blacks can’t help have their music held up as a prism to their race’s combined experiences — even abroad Masekela agitated the South African government, and passionately played what he could not verbally express through his instrument. Now one of the world’s most decorated musicians at 71, he’ll be playing selections from thoughout his career including the immortal “Grazin’ In The Grass” and last year’s Phola. (Friday@Symphony Center.)