(a)

(b)

(c)

(d)

Figure 1: (a) Characteristic burst-pause pattern of NNS. (b) Outset window of the first burst in the 30-second sample. This burst has 7 cycles, identified by letters a–g, and 6 suck cycle periods, identified by numbers 1–6. (c) Individual cycle periods converted to frequency (). (d) Plot of cycle period count versus suck cycle frequency (Hz) to demonstrate NNS frequency modulation (FM).