Fig. 4

The correlation peaks generated by ambient noise (correlation responses). a1 The locations of the microphones (blue points), signal sources (red triangles), and ambient noise sources (gray dots). a2 An enlarged view of a1. b, c The observed array CCs (b) and SI-array CCs (c). They are compared with the synthetic array CCs (b1–b5; the vertical scales are identical to that of b) and SI-array CCs (c1–c5). The numbers 1–5 indicate the synthetic test numbers in Table 2