Sources of Microstructure in Mammalian Cochlear Responses

Quasiperiodic fluctuations with frequency are observed in a variety of responses that either originate from or strongly depend on the cochlea's active mechanics. These spectral microstructures are unique and stable features of individual ears and have been most thoroughly studied in behavioral hearing thresholds and otoacoustic emissions (OAEs). While the exact morphology of the microstructure patterns may differ across measurement types, the patterns are interrelated and are thought to depend on common mechanisms. This review summarizes the characteristics and proposed origins of the microstructures observed in behavioral and OAE responses, as well as other mechanical and electrophysiological responses of the mammalian cochlea. Throughout, the work of Glenis Long and colleagues is highlighted. Long contributed greatly to our understanding of microstructure and its perceptual consequences, as well as to the development of techniques for reducing the impact of microstructure on OAE-based assays of cochlear function.