Fig. 1.

Directional tuning of sound-evoked antennal vibrations. (A) Segments of the Drosophila melanogaster antenna. The arista is rigidly coupled to a3. The arista and a3 rotate (relative to a2) in response to sound. The dashed line is the approximate axis of rotation. (B) Dorsal view of the head. The aristae are shown as thick red and black lines. The rotation of the arista–a3 structure (about the long axis of a3) is intrinsically most sensitive to air particle movement perpendicular to the plane of the arista. (C) Schematized air speed heatmap for a sound source positioned in the horizontal plane at an azimuthal angle of 45 deg. Air speed is highest in the vicinity of the contralateral antenna, owing to boundary layer effects (adapted from data in Morley et al., 2012). (D) The amplitude of antennal vibrations is plotted in polar coordinates as a function of the azimuthal angle of the sound source (adapted from data in Morley et al., 2012). This mechanical tuning profile reflects the intrinsic directionality of each arista, plus boundary layer effects.