Fig. 4.

Measured BER dependence of number of sensors. The circles are measured data with all bytes having the same total amplitude, which is equally distributed in the on-channels of the byte. The BER decreases with increasing number of sensors in the receiver array from 8 to 68 microphones with the pattern of the array shown in the Fig. S5. The dashed line marks the FEC limit which determines the maximum error rate that can still be corrected by standard FEC approaches, which is $\text{BER}=2\times {10}^{-3}$ (34). This BER limit corresponds to a minimal required receiver array with 34 sensors in our experiment. Further increasing the number of receivers will not improve the BER significantly.