Fig. 6. Intensity characteristics. (A) Frequency spectra of the acoustic random-noise stimuli. Intensity was varied in steps of 3 dB over a total range of 36 dB. `0 dB' (red) depicts the stimulus of lowest intensity, `+36 dB' (green) the stimulus of highest intensity. (B) Superimposed magnitude responses of an individual arista tip to the stimuli depicted in A. (C) Corresponding phase responses. For colour conventions, see A. _vib/_air is the response magnitude, where _vib is the vibration velocity and _air is the particle velocity. BN, background noise.