# A Planer Moving Microphone Array for Sound Source Localization
## 3 Experiment and Results
Figure 13: TF-WISE angular estimation results derived from an experiment featuring 2 sound sources (at angles of \(30^{\lx@math@degree},\,60^{\lx@math@degree},\,90^{\lx@math@degree},\,120^{ \lx@math@degree},\,\) and \(150^{\lx@math@degree}\); distances of 1.5 m (**a**) and 2 m (**b**); and a height of 1.5 m). The error between the estimated sound source angles and the true sound source angles is also shown. In Figures 25-30, the horizontal axes represent different angles, and the vertical axes represent distance. Each bar is the average estimated distance, with variation from each form of microphone array. As can be seen from the figures comparing estimation error to true distance, FPMMS is not much better than the other microphone arrays, but it is the closest to matching the 4 \(\times\) 4 linear microphone array's performance. Still, the TF-WISE algorithm has a relatively better performance in terms of variance and estimation error. Figure 16: TF-WISE angular estimation results derived from experiments featuring 5 sound sources at angles of 30\({}^{\circ}\), 60\({}^{\circ}\), 90\({}^{\circ}\), 120\({}^{\circ}\), and 150\({}^{\circ}\); distances of 1.5 m and 2 m; and a height of 1.5 m. We picked five locations from ten candidates. The error between the estimated sound source angles error and the true sound source angles at distances of 1.5 m (**a**) and 2 m (**b**) is also shown. Figure 15: TF–WISE angular estimation results derived from using 4 sound sources at angles of 30\({}^{\circ}\), 60\({}^{\circ}\), 90\({}^{\circ}\), 120\({}^{\circ}\), and 150\({}^{\circ}\); distances of 1.5 m and 2 m; and a height of 1.5 m. We picked four locations from ten candidates. The error between the estimated sound source angles and the true sound source angles at distances of 1.5 m (**a**) and 2 m (**b**) is also shown. Finally, our third experiment was focused on height estimation. The general procedure is depicted in Figure 31. Here, the FPMMS was applied to a robot placed a height of 1 m above the floor. However, the contrast group microphone arrays were placed horizontally, making a height estimation comparison impossible. Also, the rotating action is in planar, making no difference. Thus, for a fair comparison, we manually put arrays in the contrast group in the vertical direction. The speaker heights were set to 0.7 m and 1.5 m because, usually, the person's height minus 10 cm to 20 cm is the height of the mouse. To mimic children and adults, 0.7 m and 1.5 m could also be appropriate choices. The results are shown below:  
Figure 9:0 MUSIC angular estimation results derived from experiments featuring 2 sound sources at angles of 30\({}^{\circ}\), 60\({}^{\circ}\), 90\({}^{\circ}\), 120\({}^{\circ}\), and 150\({}^{\circ}\); distances of 1.5 m (**a**) and 2 m (**b**); and a height of 1.5 m. The error between the estimated sound source angles and the true sound source angles is also shown. Figure 9:1 MUSIC angular estimation results derived from an experiment featuring 3 sound sources at angles of 30\({}^{\circ}\), 60\({}^{\circ}\), 90\({}^{\circ}\), 120\({}^{\circ}\), and 150\({}^{\circ}\); distances of 1.5 m (**a**) and 2 m (**b**); and a height of 1.5 m. The error between the estimated sound source angles and the true sound source angles is also shown. In Figures 32-37, FPMMS-P2 (pattern 2, \"Acute Triangle\") generally shows height estimation results nearest to the 4 \(\times\) 4 (16) linear microphone array. Also, in Figure 23, FPMMS-P2 is shown to perform better than the other patterns. The circular array is just behind FPMMS-P2 in terms of performance. Comprehensively considering the results, we believe that the microphone pairs in the \"Ba Zi\" pattern have two special features: First, unlike pattern 1, the microphone pairs in the \"Ba Zi\" pattern form the line closer to the pure vertical line, which means that angle estimation is more precise.