# Improving Engineering Design Using Smart Evaluation of Indoor Acoustical Climate of Dining Places
## 4 Acoustical Analysis of Dining Places  
According to [PERSON] et al. [48], dining places (for example, restaurants) can be divided into five types depending on the consumption type: quick service (fast food), fast casual, medium scale, moderate, and good cuisine. Dining places can also be divided into three categories based on the dish consumption style: centralised, separated, and scattered. In centralised restaurants, clients sit at a table. Many dishes are placed around a central table in separate dining rooms--for example, a buffet. Guests walk along the table and pick the dishes of their choice. They then consume it alone or with other people. In scattered dining rooms, guests select dishes from a menu and then take them to their tables. The style of the dining establishment may influence conversation behaviour. With a higher crowd density, the sound pressure level inside the enclosure also increases [39; 43]. Dining places include high-quality restaurants serving sophisticated meals, family restaurants, affordable cafes, and fast-food restaurants. Restaurants generally provide tables and chairs for clients, with meals prepared in an attached kitchen equipped with crockery, cutlery, and tableware that vary in quality and concept. The climate of a dining place is often what clients return for, despite the excellent food and quality of service. [PERSON] et al. [54] gave a typology of dining places divided into five extended classes based on five sets of typologies, such as fast food, service, medium, moderately exclusive, exclusive, and business. In terms of design, dining establishments tend to differ based on four common design strategies: the use of materials or finishing, space size (geometry), and types and concepts of dining space. However, other findings claim that the classification of eating establishments can vary depending on who visits them and what they do [55]. Based on literature data [56] and plans of actual dining places, an analysis of this type of room was carried out, and individual elements affecting the acoustic properties of dining places were selected and subjected to further analysis:  
* The rooms' dimensions and geometry;
* The layout of the rooms, including the number of occupants;
* The use of sound-absorbing materials. The acoustic properties were analysed using Odeon software (version 13.1 Industrial). The analyses were performed for a simplified example of a 300 m\({}^{2}\) restaurant. To exclude other factors, such as the complex shape of the enclosure or different arrangements of interior furnishings, which affect the acoustic climate of the enclosure, the configuration and materials were significantly simplified. Figure 2 presents an overall view of the simulated restaurant. The main aspect of the computer analysis was to assess the influence of different parameters on speech intelligibility. * Different numbers of tables in the enclosure: 9 (low capacity), 25 (average capacity), and 42 (high capacity) tables, which represent almost empty, average, and overcrowded restaurants, respectively;
* Differing sound absorption of the ceiling, with sound absorption coefficients \(\alpha_{\text{p}}=0.1\), 0.4 and 0.8 representing a wide range of materials used in dining places;The goal of the analysis was to indicate how speech intelligibility depends on the density of the tables and the absorption of the ceiling simultaneously. The sound absorption parameters for each material used in the analysed enclosure are presented in Table 1. The sound scattering parameters of the materials were not considered during the computer analysis (a value of 0.05 was assigned for all surfaces). The location of the absorbing materials was also not considered, as it has been shown that it has no significant effect on improving speech intelligibility in the room [6]. For the analysis, in the simplified situation, only one location of the loudspeaker was taken into account. The sound source was located in the upper corner of the simulated restaurant space.