Background FIGURE 1- Parakeet audiogram. Data

from Brittain-Powell et al. (2002) Budgerigar’s (parakeets) thresholds for detection of changes in complex sounds, such as amplitude modula-tions, are comparable to those of human listeners (Dooling et al. 1985, 1987; Dent et al., 2002; Carney et al., ARO 2013). A better characterization of their peripheral auditory system would contribute to modeling e!orts that relate physiology to perception. Parakeet auditory thresholds are relatively low, but chie"y con#ned to lower frequencies (Fig.1). The inner ear morphology of birds is quite di!erent relative to mammals (Fig.2) and is known in quantitative detail for the parakeet (Manley et al. 1993): short papilla (~2.5 mm) with ~5400 hair cells. Furthermore, there is evidence for a traveling wave at work in the bird ear (Gummer et al. 1987), however hair cell somatic motility appears absent (He et al. 2003; Koppl et al. 2004). The middle ear consists of a single ossicle (columella). Otoacoustic emissions (OAEs) provide a non-invasive strategy for characterizing the tuning of the auditory pe-riphery in both mammals (Shera et al. 2002, 2010; Joris e