Benefit of a commercially available cochlear implant processor with dual-microphone beamforming: a multi-center study - Wolfe, J; Parkinson, A; Schafer, EC; Gilden, J; Rehwinkel, K; Mansanares, J; Coughlan, E; Wright, J; Torres, J; Gannaway, S (Otol Neurotol, 2012)