What is "HB"? "It's two quite unusual found sound pieces and two musique concrète works based on each other's works," explains English. In other words, López and English each submitted to the other a field recording piece, then composed a new piece from the other guy's field recording. The result is resolutely sombre going on obscurantist: occulted birdsongs, unidentified tremors, delicate but disquieting sounds from a jungle that could be either of the wild or urban kind. This soundworld lies somewhere between mystery and mystification.