High-order auditory filters.

The past year has seen some important advances in our understanding of central auditory function. Several central auditory neurons that differ from those in the periphery in their selectivity for various spectral and temporal parameters of complex sound have been described. Although central specializations for the processing of complex sound have been known for some time, recent findings suggest that these high-order filter properties are more widespread than previously thought. Significant progress has been made in our understanding of the neural mechanisms by which some high-order filter properties, such as delay-tuning, amplitude-tuning, and complex frequency tuning are performed by the central auditory system. New evidence has clarified the role of high-order auditory filters in auditory learning and perception, and the regions in which they are found.