Fig. 8. Accelerometer recordings demonstrating that electrical stimulation of sonic muscles yielded carapace vibrations. Remotor muscle stimulation, and stimulation of both the remotor and promotor muscles simultaneously, resulted in body vibrations, while stimulation of promotor muscles did not cause body vibrations. Electrical stimulations involving both muscles created vibrations most similar in waveform and intensity to naturally produced sounds. Horizontal bars indicate the periods of stimulation. Scale: 5 mV, 150 ms.