Figure 1.

(A) Mean spike rate (spikes/s) in response to 16 repetitions of unmodulated broadband noise (200 ms duration, interstimulus interval 1800 ms), presented at a level of −4 dB (re: 0.1 Pa). Tadpoles in stages 38–41 (n = 6) showed significantly reduced activity (∗) to unmodulated noise compared with tadpoles in other developmental stages (n = 6 for stages 25–30; n = 11 for stages 31–37; n = 7 for stages 42–45). (Error bar = 1 SD.) (B) Spike rates in response to unmodulated noise for four tadpoles with head/oval window regions unblocked (baseline, white fill) vs. blocked by earmuffs (shaded). Data at stage 39 represent means from two animals.