An attempt to use the Lombard effect to prescribe effective acoustical treatments in a university cafeteria space

摘要

The Lombard Effect is a psychoacoustic phenomenon by which people subconsciously raise the volume of their speaking voice in order to compensate for high levels of background noise. This becomes particularly problematic in highly populated spaces such as cafeterias or restaurants. It becomes difficult for people to easily communicate within these rooms, creating an uncomfortable dining experience. In this article, the authors investigated if and how the Lombard Effect manifests itself within a cafeteria-type space, Dewick-MacPhie Dining Hall at Tufts University, and whether acoustical treatment is required. Anecdotal evidence from staff and students as well as personal experience as students of Tufts University indicate that the noise issues may result in part from the Lombard Effect. Initial investigation shows noise levels exceeding NC-70, where NC-35 to NC-45 is ideal for cafeteria spaces. Mathematical models of the space were created based on physical measurements as well as experimental sound level data in order to assess the efficacy of certain acoustical treatments in the mitigation of the high noise levels and possible consequences of the Lombard Effect on the space. Absorption via custom printed panels and catenary banners is prescribed to increase the absorption in the room by 1097 Sabins.