# Fast Sound Source Localization Based on SRP-PHAT Using Density Peaks Clustering
## 5 Simulations
### Comparison of Sound Source Localization  
A parameter \(V\) called the localization success rate was used to compare the SRP-PHAT and ODB-SRP-PHAT.  
\[V=\frac{N_{succ}}{N_{total}} \tag{14}\]  
where \(N_{total}\) is the total localization times, which was taken as 100 in this section. \(N_{succ}\) is the successful localization time. The tolerance for both the azimuth and elevation was set as \(10^{\circ}\) when SRP-PHAT was used.  
When the reverberation time was 300 ms, the results of localization under situations of six different SNRs are shown in Figure 7a. When the SNR was 5 dB, \(V\) was only about 80% for SRP-PHAT, which was much smaller than that for ODB-SRP-PHAT. ODB-SRP-PHAT exhibited good performance of localization even under extremely low SNRs. The higher the SNR, the bigger the value of \(V\) for both methods. When the SNR was 30 dB, \(V\) approached 100%.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Node**} & \multicolumn{2}{c}{**20 ms**} & \multicolumn{2}{c}{**300 ms**} & \multicolumn{2}{c}{**500 ms**} & \multicolumn{2}{c}{**700 ms**} & \multicolumn{2}{c}{**900 ms**} \\ \cline{2-11}  & \(\theta\) & \(\varphi\) & \(\theta\) & \(\varphi\) & \(\theta\) & \(\varphi\) & \(\theta\) & \(\theta\) & \(\varphi\) & \(\theta\) & \(\varphi\) \\ \hline \(q_{1}\) & 45 & 38 & 45 & 38 & 45 & 38 & 45 & 37 & 45 & **37** \\ \(q_{2}\) & 45 & 57 & 45 & 57 & 45 & 57 & 45 & **56** & 45 & **59** \\ \(q_{3}\) & 75 & 38 & 75 & 38 & 75 & 38 & **74** & 38 & **74** & 38 \\ \(q_{4}\) & 75 & 56 & 75 & 56 & 75 & 56 & 75 & 56 & 75 & 56 \\ \(q_{5}\) & 105 & 38 & 105 & 38 & 105 & 38 & 105 & 38 & 106 & 38 \\ \(q_{6}\) & 105 & 56 & 105 & 56 & 105 & 56 & 105 & **57** & 105 & **57** \\ \(q_{7}\) & 135 & 38 & 135 & 38 & 135 & 38 & 135 & **37** & 135 & **37** \\ \(q_{8}\) & 135 & 57 & 135 & 57 & 135 & **58** & 135 & 57 & 135 & **58** \\ \hline \hline \end{tabular}
\end{table}
Table 2: Identified sound source (cluster center) coordinates with different reverberation time.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Node**} & \multicolumn{2}{c}{**10 Frames**} & \multicolumn{2}{c}{**20 Frames**} & \multicolumn{2}{c}{**30 Frames**} & \multicolumn{2}{c}{**50 Frames**} & \multicolumn{2}{c}{**100 Frames**} & \multicolumn{2}{c}{**150 Frames**} \\ \cline{2-11}  & \(\theta\) & \(\varphi\) & \(\theta\) & \(\varphi\) & \(\theta\) & \(\varphi\) & \(\theta\) & \(\varphi\) & \(\theta\) & \(\varphi\) & \(\theta\) & \(\varphi\) \\ \hline \(q_{1}\) & 45 & **39** & 45 & 38 & 45 & 38 & 45 & 38 & 45 & 38 & 45 & 38 \\ \(q_{2}\) & 45 &Simulations were also carried out for five situations of reverberation time under an SNR of 30 dB. As shown in Figure 7b, when the reverberation time was 20 ms, both methods achieved ideal results. As the reverberation became stronger, the values of \(V\) for both methods went down. However, even when the reverberation time was as long as 900 ms, the value of \(V\) for the proposed method could be above 90%, better than SRP-PHAT. This indicates that ODB-SRP-PHAT had good anti-reverberation ability.