# Echo Analysis in Iberian Bullfighting Arenas Through Objective Parameters and Acoustic Simulation 1
## 4 Results and Discussion
### Echo Criterion EK in the Study Cases
#### 4.2.3 Results in the Bullring of Las Ventas  
In the Las Ventas bullring in Madrid, out of the 71 combinations recorded in the audience area, a risk of echo for speech is present in a first approximation in 9 combinations: S1-R2, S1-R11, S1-R12, and S1-R16; in S2-R17; in S3-R4; and in S4-R1, S4-R2, and S4-R5. Table 7 shows the values for these echo parameters and other acoustic parameters in the audience area, while Table 8 shows the results for the same parameters when the sound source and receiver are both in the ring. From the inspection of the IRs and according to the significant reflection times in Table 7, it can be concluded that no echo is present in any of the combinations shown for the music, and that in the three positions of S4, they are not real echoes but rather unwanted background noise. The rest of the combinations shown in the table for the other sources and whose results appear in bold are interpreted as echo signals. Furthermore, in the remaining combinations for the other sound sources, it is worth noting that it is the only bullring of the four cases analysed that presents an echo in certain positions of the grandstands with \begin{table}
\begin{tabular}{l c c c c c c c c c c} \hline \hline  & **EK\({}_{\text{speech}}\)** & **EK\({}_{\text{music}}\)** & \(\begin{array}{c}T_{\text{speech}}\\ \text{(ms)}\end{array}\) & \(\begin{array}{c}T_{\text{music}}\\ \text{(ms)}\end{array}\) & \(\begin{array}{c}d_{\text{s-r}}\text{ (m)}\end{array}\) & \(D_{\text{50m}}\) & STI & \(\begin{array}{c}T_{\text{sm}}\\ \text{(ms)}\end{array}\) \\ \hline S2 Ring & & & & & & & & & & \\ Picador Line & & & & & & & & & \\ \hline R1 & 1.07 & 1.07 & 2824 & 2824 & 29.3 & 0.54 & Fair & 0.54 & Fair & 104 & Fair \\ R2 & 1.19 & 1.27 & 2668 & 2668 & 31.3 & 0.45 & Fair & 0.52 & Fair & 126 & Fair \\ R10 & 1.05 & 1.02 & 1929 & 1929 & 41.3 & 0.62 & Good & 0.55 & Fair & 103 & Fair \\ \hline S3 Music & & & & & & & & & & \\ band & & & & & & & & & & & \\ R1 & 1.07 & 0.94 & 2326 & 2326 & 25.3 & 0.60 & Good & 0.62 & Good & 81 & Good \\ \hline S4 Bugle and & & & & & & & & & & & \\ timpani & & & & & & & & & & & \\ R13 & 1.22 & 1.17 & 1769 & 2459 & 24 & 0.77 & Good & 0.67 & Good & 60 & Good \\ R14 & 1.08 & 1.03 & 2704 & 2704 & 25.9 & 0.69 & Good & 0.64 & Good & 65 & Good \\ \hline S5 Public & & & & & & & & & & \\ R8 & 1 & 0.92 & 1701 & 1711 & 20.0 & 0.78 & Good & 0.74 & Good & 44 & Good \\ R13 & **1.21** & 1.53 & **72** & 77 & 55.5 & 0.58 & Good & 0.61 & Good & 88 & Good \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Echo and other acoustic parameters in the Seville bullring in the audience area. In bold interpreted as an echo. the source in the centre of the ring, which can be attributed to the fact that in this bullring, the seating area reaches great heights, and this contributes to the focusing of the sound. The symmetry of the positions in the bullring of S1-R2 and S1-R12 on the one hand, and of S1-R11 and S1-R16 on the other hand, is manifested in the results of all the parameters in Table 7. The acoustic parameters of speech intelligibility present acceptable or good values, and deteriorate in receivers located at great distances from the source, wherein a risk of echo is detected for speech. As an example, Figure 14 presents the speech echo parameter and the energy decay curve and Schroeder curve in the S2-R17 combination in Las Ventas bullring, and shows the strong reflection and the jump in decay energy at 223 ms.