Figure 4. Acoustic features of rumbles emitted in response to sound playbacks.

Mean (±1 SEM) for acoustic features across the three contexts (control  =  pre-stimulus phases of trials; noise  =  during stimulus or post-stimulus phases of white noise trials; bees  =  during stimulus or post-stimulus phases of bee trials). Results of pair-wise tests showed that bee and white noise rumbles were statistically different from controls for mean F_o and F_o range, and that bee rumbles were significantly different from white noise and control rumbles for second formant frequency location.