Rose Bishop and Heather Neuenschwander performing at the James Theater — courtesy of the artistsRose Bishop and Heather Neuenschwander, two classical flutists who recently released the duo album Unseen/Unheard, performed a release recital on Sept. 26 at the James Theater. Rose Bishop and Heather Neuenschwander performing at the James Theater — courtesy of the artistsRose Bishop and Heather Neuenschwander performing at the James Theater — courtesy of the artistsRose Bishop and Heather Neuenschwander performing at the James Theater — courtesy of the artistsRose Bishop and Heather Neuenschwander performing at the James Theater — courtesy of the artistsAlso very good to hear is two flutists performing new music. Relative to the standard concert flute (whose range begins at Middle C) the alto is a fifth lower, and bass flute an octave lower. Bishop’s bass flute sound has multiple textures, sounding sometimes like a saxophone or English horn. They may not have invented the genre of alto and bass flute duets, but the commissions and their performances significantly enlarged the repertoire for that instrumentation.