Otoacoustic emissions in a song bird

Synchronously evoked otoacoustic emissions (SEOAEs) were found in about two thirds (61%) of 56 ears of the starling Sturnus vulgaris. They appeared with rather broad synchronization widths (about 200 Hz) and predominantly at frequencies in the upper half of the hearing range of this bird. SEOAEs varied in level from below -30 dB to 2 dB SPL and showed typically nonlinear intensity functions. The emissions were present even following extirpation of the middle-ear muscle and could be suppressed by anaesthetics. Using Halothane, it was possible to determine the time course of this suppressive effect. Using second tones, typical iso-suppression tuning curves were obtained. The similarities and differences between the characteristics of these SEOAEs and emissions in other nonmammals and in mammals are discussed with regard to anatomical differences in inner-ear structure.