Recent advances in computing and auditory neuroscience have now made it possible to produce highresolution, real-time simulations of major portions of the human auditory pathway, including high resolution, real-time models of the cochlea, major cell-types of the cochlear nucleus, lateral and medial superior olivary complex, as well as polyphonic pitch perception based on combination-sensitive cells measured in inferior colliculus and auditory cortex, all running live on a notebook computer. These technologies are the foundation of Audience's Voice Processor chip, which provides advanced two-microphone noise reduction for cell-phones. The design of the simulated system required many careful decisions about what biological details to include, in order to preserve functional biological realism, while meeting the constraints of real-time implementation and commercial product realization.