# Improving Engineering Design Using Smart Evaluation of Indoor Acoustical Climate of Dining Places
## 6 Verification of the Method  
To verify the method, a subjective assessment of the acoustical climate of the dining places was performed. The literature has clearly shown that client satisfaction influences the effect of emotion on revisit intention [60]. Two different restaurants were chosen, and the results of the evaluation are presented in Table 5. Both restaurants are located in the same city (Warsaw, Poland) and district, 3.6 km away from each other. They are designed as restaurants for family and friend meetings. These restaurants were chosen because of their different designs, and both were well known to the people assessing the acoustical climate. Images of both restaurants are presented in Figure 6.  
In this study, the objective measurements of reverberation time, background noise, and speech intelligibility were not performed in these restaurants because the main goal was the subjective assessment of the general impression of the acoustical climate of both enclosures. Restaurant A: Casual dining style with a simple enclosure without any absorptive materials or partitions dividing the enclosure into smaller areas. The room volume was approximately 80 m\({}^{3}\). Approximately 15 tables are placed tightly next to each other with leather chairs. There is also a bar counter in the corner with noisy machines, such as coffee or juice machines. \begin{table}
\begin{tabular}{c c c} \hline \(\mathbf{W_{n}}\) & Restaurant A & Restaurant B \\ \hline \(\mathbf{W_{A}}\) & 3 & 5 \\ \hline \(\mathbf{W_{V}}\) & 3 & 3 \\ \hline \(\mathbf{W_{C}}\) & 2 & 4 \\ \hline \(\mathbf{W_{N}}\) & 2 & 2 \\ \hline \(\mathbf{W_{R1}}\) & 0 & 2 \\ \hline \(\mathbf{W_{R2}}\) & 0 & 2 \\ \hline \(\mathbf{sum}\) & \(\mathbf{10}\) & \(\mathbf{18}\) \\ \hline \end{tabular}
\end{table} 
Table 5: Acoustical evaluation of two restaurants. Restaurant B: moderate upscale/casual dining style with a complex enclosure with three coupled rooms, each approximately 30-50 m\({}^{3}\). There are many absorptive elements, such as curtains, soft couches and bookshelves. Twenty tables were placed randomly in the enclosure with some free space between them. There is a bar counter in one of the coupled rooms with noisy machines, such as coffee or juice machines. The acoustical evaluation showed that the acoustical climate in Restaurant A was sufficient, but attention should still be paid to potential acoustic problems, such as verbal communication quality caused by reverberation noise. The acoustical evaluation of Restaurant B shows that the room does not suffer from common acoustic problems, such as excessively long reverberation time. The architectural parameters (volume, shape, and partitions) and acoustic parameters (absorption, capacity, and background noise) were chosen correctly, and verbal communication was good. Subjective assessments were performed using an online survey. For the subjective assessment, 10 people (seven men and three women, aged 35-55 years, with education from primary to higher) were chosen from customers of both restaurants. All participants were regular customers of both restaurants; therefore, the subjective assessment was averaged based on their long-term experience and was not based on a single day's visit. They were asked to answer four questions concerning the quality of the different aspects presented in Table 6. Customers were first asked to assess background noise and music. These two elements influence the communication quality and overall atmosphere the most. The results of the subjective assessment are shown in Table 7, along with the individual results. In both restaurants, the background music was evaluated as \"acceptable\". The noise in restaurant A was assessed as \"not acceptable\"; therefore, the vocal communication and atmosphere were evaluated differently. For Restaurant A, with one simple enclosure and poor absorption, verbal communication was assessed as \"problematic\" and the atmosphere as \"noisy\". For Restaurant B the results show \"good\" verbal communication and a \"l