## 5 Simulation Results and Analysis
When the number of snapshots is between 20 and 90, the RMSE results of the SSC-MVDR algorithm in Figure 5 is also significantly lower than that of other algorithms. Figure 4: DOA estimation accuracy results obtained by the MVDR method, the MUSIC method, the Root-MUSIC method, the TLS-ESPRIT method, the PM method and the SSC-MVDR method when the number of snapshots is fixed at 100, and the intensity of the acoustic source is gradually increased from \(-20\) dB to 20 dB. Figure 3: Normalized spatial power spectrums obtained by the MVDR method, the MUSIC method, the PM method and the SSC-MVDR method when the acoustic source intensity is \(-10\) dB and the snapshot number is 30. Although the interference acoustic source in the far field has been considered in the above simulation (that is, an interference acoustic source with an intensity of 30 dB and a direction of 60 degrees is always included in the simulation settings), it is still necessary to perform simulation and analysis for the case of multiple interference acoustic sources. The results of the direction estimation accuracy under multiple interference acoustic sources are shown in Figure 6. In Figure 6, the intensities of the multiple interference acoustic sources are set to be the same, and the interference-to-noise ratio (INR) of each interference is gradually increased from 0 dB to 50 dB. Besides, \(N_{I}\) represents the number of interference acoustic sources. For example, \(N_{I}=3\) means that there are 3 interference acoustic sources in the far field at the same time, their directions are 60 degrees, 10 degrees, and \(-20\) degrees, respectively. As can be seen from Figure 6, the three curves corresponding to different numbers of interferences are almost coincident. Figure 5: DOA estimation accuracy results obtained by the MVDR method, the MUSIC method, the Root-MUSIC method, the TLS-ESPRIT method, the PM method and the SSC-MVDR method when the acoustic source intensity is fixed at \(-10\) dB, and the number of snapshots is gradually increased from 10 to 100. Figure 6: DOA estimation accuracy results obtained by the SSC-MVDR algorithm when there are multiple interfering sound sources with the source intensity gradually increased from 0 dB to 50 dB. Finally, the influence of the direction interval, which is one of the important parameters of the SSC-MVDR algorithm, on the performance of the proposed algorithm is analyzed by simulation. In Figure 7, the horizontal axis is marked as the window width, that is, the width of the direction interval \(\Theta\). The three curves in Figure 7 are the accuracy results of DOA estimation obtained by the SSC-MVDR algorithm when the parameter \(\theta_{e}\) takes different values, where \(\theta_{e}\) represents the deviation of the center of the direction interval from the true DOA. It can be seen from Figure 7 that when the width of the direction interval is in the range of 10 degrees to 20 degrees, the RMSEs obtained by the SSC-MVDR algorithm is significantly lower than that when different window widths out of the above range is used. The reason for the above results is that when the center of the direction interval deviates from the true DOA and the selected direction interval is too narrow, the actual DOA of the acoustic source will fall outside the selected direction interval, thus the obtained DOA estimation must be wrong. However, when the selected direction interval is too wide, it will cause the beam response segment in the direction interval to contain some unwanted or even unfavorable information, such as other nulls in the beam response that are independent of signal self-cancellation.