When she is in concert, Oumou Sangare prefers, initially, to be heard and not seen. Her seven-piece band takes the stage before her, kitted out in mud-dyed garments and the occasional horsehair head-dress, blending their traditional and modern instruments into a rhythmic groove. Two young female backing singers begin dancing and twirling calabashes in the air - large bowls decorated with loosely-tied cowrie shells - catching them again to resounding thwacks.