Abstract: Animal Aeroacoustics is the study of the acoustics and biology of the sounds animals make when they fly. We begin by exploring an acoustic mechanism that, while catastrophic for aircraft, many birds use to communicate: aeroelastic flutter. The tail of hummingbirds is essentially a 'musical instrument': by evolving different shapes of tail-feathers, different species produce a range of species-specific sounds. Moreover, we demonstrate three different types of interactions between adjacent fluttering feathers that enhance the acoustic diversity of sound that is produced. Next, we explore how hummingbirds use behavior to modulate the sounds they produce with their tail during a courtship dive, as heard by a recipient, a female. We recorded dives using two 'acoustic cameras' (phased arrays of microphones that use beamforming to localize sound) to track the bird through 3D space. We demonstrate that male Costa's Hummingbird (Calypte costae) places the female in a part of the sound field in which the Doppler shift is minimized, while simultaneously employing strategies to maximize loudness. Finally, we discuss ongoing projects on the hum of hummingbirds, buzzing of bee and mosquito wings, as well as work on the silent flight of hunting owls.