Figure 5
The leakage factor of the dynamic squelch sets the tradeoff between transmitting all local signals (i.e., soft calls) and suppressing leaked signals (i.e., loud residual echoes). (a) In a hierarchical network among 3 males, we set three different leakage factors, 0 dB (left), − 20 dB (middle), and − 60 dB (right). Shown are example spectrograms in which the top bird T produces a soft call (MicSep T) simultaneously with a loud call in L (MicSep L). A high dynamic squelch (left) produces a chopped version of T’s call on the Speaker R signal (green arrow). A midrange setting of the leakage factor (middle) preserves T’s call on Speaker R. Absence of dynamic squelching (right) produces a superposition of both calls on Speaker R, which entails that bird R can hear residual echoes of bird L (orange arrow). (b) Top: example spectrograms of a soft call in T (speaker R) and the response in R (MicSep R, purple) when L is silent. Bottom: root-mean square (RMS) of MicSep R signal averaged over instances in which T produces soft calls during silence (solid line) and instances in which T produces a soft call simultaneously with a loud call in L (as in a, dashed line). Time zero is the (visually detected) onset of the call in T. In case of a high leakage factor (0 dB, top), R fails to respond to concurrent calls in T (dashed line is flat). In the case of a midrange or low leakage factor setting (− 20 dB and − 60 dB), R responds similarly to both isolate and jamming calls (full and dashed lines are similar). Instances (7/540) in which T called into R’s response (in the interval [100,1000] ms) were excluded from the plot, although their inclusion had essentially no visual effect on the curves.
