Auditory System Characterization

The world is full of sounds—rustle of leaves, whistle of winds, and bustle of cities—and in our everyday lives, we enjoy music and pleasant conversations with friends and families. Such auditory communications play highly significant roles in social interactions in many animal species including humans, songbirds, crickets, and so on, but they would never be accom-plished without the specialized module in the brain; the auditory system. The three main functions of the auditory system are to separate, localize, and identify sound signals we receive at the cochlea. To perform these tasks, the auditory system became sophisticated during the course of evolution, and now reached such an amazing level where coincidence detectors in owls can identify interaural time differences with the precision of microseconds (Moiseff and Konishi, 1981; Konishi, 2003), and hair cells in the vertebrate ear can detect a tip movement of only a tenth of a nanometer (Sellick et al., 1982; Crawford and Fettiplace, 1985; Hudspeth, 1989, 1997). Moreover, a trained ear can establish a sense of “absolute pitch ” (Zatorre, 2003; Levitin and Rogers, 2005), and even listen out and transcribe a single instrument from a musical piece played by an orchestra. How can the brain perform such outstanding feats? Although the auditory system work