Fig. 3. (A) Responses of the same structures as represented in Fig. 2, but after the extrastapes had been severed. The tympanic membrane response is represented in black. Note that the responses of both footplate (red) and operculum (orange) have dropped to match the `background' response of the parotic crest (green). (B) Phase lag between the tympanic membrane and the footplate (black) and between the footplate and operculum (red) in the same frog after the extrastapes had been cut. Although the footplate no longer shows the typical phase relationship with the tympanic membrane (represented in Fig. 2B), the responses of footplate and operculum remain in phase.