Technical Note An analytical model to evaluate the cocktail party effect in restaurant dining rooms: A case study Francesco Leccese, Giuseppe Tuoni, Giacomo Salvadori, Michele Rocca ⇑ Dept. of Energy Engineering, Systems, Territory and Constructions (DESTeC), LIghting and Acoustic Laboratory (LIA), University of Pisa, School of Engineering, Largo Lucio Lazzarino, Pisa 56123, Italy article info Article history: Received 27 February 2015 Received in revised form 16 June 2015 Accepted 22 June 2015 Available online 11 July 2015 Keywords: Acoustic comfort Cocktail party effect Acoustic panels Restaurants dining rooms Acoustic simulation software abstract This paper proposes the use of a simplified analytical model to evaluate acoustic conditions in restaurant dining rooms required for ensuring the intelligibility of conversations. The model is useful for design applications and is suitable for evaluating the maximum number of speakers present in a restaurant room in order to ensure intelligibility of conversations taking place at each table in the presence of background noise caused by conversations at other tables. The maximum number of speakers is studied in relation to the sound level difference between useful and disturbing sound, sound absorption of the room, and the average speaker–listener distance. The model is applied to the case of a dining hall in a multipurpose centre, which is currently in the planning stage. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction The present study aims at investigating a particular acoustic phenomenon known as ‘‘cocktail party effect’’ [1–5] which can significantly affect the level of comfortable acoustic conditions in restaurant dining rooms. A simplified analytical model is devel- oped for assessing acoustic comfort conditions and good intelligi- bility of the conversation that is taking place at a generic table with respect to the background noise generated by the conversa- tions taking place at the other tables. The analytical model is useful for design applications and suitable to evaluate the maximum number of speakers that can be present in a restaurant room. The maximum number of speakers is evaluated as a function of the sound level difference between useful and disturbing sound, sound absorption of the room and average speaker–listener distance. The Authors have already dealt with the problem of acoustic comfort in dining rooms [6] by examining possible acoustic corrections of the cafeteria/self-service of the Ospedale della Versilia (Lucca, Tuscany region, Italy). In this paper the analytical model has been applied to the case study of the dining hall of a multipurpose centre, which is currently in the planning stage. The results obtained correspond well with those obtained by using CATT Acoustic simulation software [7]. The results obtained with the analytical model can also be used, with appropriate modifica- tions, to adjust sound in other environments such as waiting rooms, hotel lobbies, and shopping malls. 2. The cocktail party effect in dining rooms In order to provide restaurant dining rooms with a suitable comfort level, it is necessary to ensure that the conversation taking place at one table may be held in a mutually understandable way to avoid any background noise from conversations going on at the neighbouring tables (as a rule, the exposure level to background noise from external sources has been proven to be negligible in such rooms). When hosting several customer groups simultane- ously, restaurants are affected by very unpleasant background noise, which compels each of the speakers to raise their voice in an effort to make themselves heard by people sharing the same table. In a completely instinctive manner, all of the other speakers imitate this behaviour, thus adding to the already perceived back- ground noise, which keeps on increasing in a chain reaction known as the ‘‘cocktail party effect’’. Such an effect is particularly notice- able at banquets where dining rooms are crowded and guests are more than usually concerned about standing out as talkative and engaged partners. It is a common practice in the design of dining rooms, even for those to whom skilled chefs attract a sophisticated clientele, to pay particular attention to the architecture and the decor and completely ignore the noise problems. http://dx.doi.org/10.1016/j.apacoust.2015.06.012 0003-682X/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +39 349 0942629. E-mail address: michele.rocca.au@gmail.com (M. Rocca). Applied Acoustics 100 (2015) 87–94 Contents lists available at ScienceDirect Applied Acoustics journal homepage: www.elsevier.com/locate/apacoust