# Improving Engineering Design Using Smart Evaluation of Indoor Acoustical Climate of Dining Places
## 3 Assessment of Dining Places' Acoustical Climate  
The collected literature material concerns different types of dining places, including but not limited to the following:  
* Restaurants [20; 21; 28; 31; 34; 36; 37; 38; 39; 40; 41; 42; 43];
* Bars and clubs [26; 44; 45; 46];
* School cafeterias/ canteens [24];
* Fast-food restaurants [47; 48];
* Other restaurant types [4; 26; 27; 30; 49; 50]. Several studies have referred to acoustic comfort in restaurants and catering facilities. Figure 1 shows the proposed classification of acoustic comfort in dining places. It was shown that many non-acoustical parameters influence the acoustic comfort of dining places, such as the user's character or the character of the restaurant. These include architectural parameters, such as the design character, layout/arrangement of tables, or density/occupancy of a diner; and acoustical parameters, such as ambient and equipment noise. The authors also indicated that the sound of conversations among customers and the density of occupancy control our perception of noise in the restaurant. The main topic discussed in the literature is noise in restaurants and catering premises. Noise is the most common problem in the evaluation of the acoustic climate of dining places and should be prioritised to improve the environment and enhance the overall dining experience. The sound might be chaotic and complex and should be controlled to make it more pleasant for guests [35]. Recently, the problem of noisy climates in restaurants and bars has been increasingly observed. Noise was found to impact the perception of the taste, aroma, and texture of food and beverages. Noise seems to selectively weaken the capability to distinguish sweet and sour tastes, whereas detecting other taste impressions was rather intact [51]. Modern restaurant design trends have unintentionally resulted in excessive noise levels. The restaurant design included an open kitchen, wooden floors, and no tabelcoths. Modern restaurant designs are characterised by open spaces with neat, hard surfaces and no carpets, curtains, or tabelcoths, which results in sound waves being reflected rather than absorbed. There are many potential noise sources in such spaces, including but not limited to kitchens, clients, music, environmental systems, street traffic, and other companies [20]. The sound level and sources in restaurants can negatively affect acoustic comfort. A correlation was revealed between the variability and duration of acoustic comfort. A restaurant's acoustic comfort is strongly correlated with communication and children streaming [48]. A higher noise level can disturb the culinary experience, smell, and taste perception. Speech comprehensibility can be affected in noisy dining places, for example, due to their location near a high-traffic street, open kitchen, inadequate decoration of tables, and speakers' behaviour. Long-lasting exposure to sound and noise at high decibel levels affects health, well-being, social interactions, and communication. It directly influences a human's acoustic comfort preferences during eating [50], and noise also affects the perception of food and drink [51]. It may also influence the aroma, flavour, and textural properties of food and drinks. Typical noise levels in dining establishments vary for different authors: from 57 to 75 dB [36; 47] through 60-80 dB [45; 52] to over 90 dB [44]. Typical noises can be classified into three groups: natural, technological, and human [42]. It included noise sources such as air conditioning systems, service signals, kitchen noise or chatting people, or even outside  
Figure 1: The concept of acoustical climate classification in dining places [50]. traffic and other businesses [20]. In the case of human noise, acoustic comfort was also correlated with children's behaviour [48]. Noise exerts a significant influence on speech intelligibility and causes the [PERSON] effect.