Occupancy-based analysis and interpretation of soundscape auditory complexity: Case of a campus restaurant

This work presents a perceptually-inspired parametric study of soundscape auditory complexity perception in a confined public eating space that is a student campus restaurant. The responses to five aspects of auditory complexity perception are investigated via an on-site restaurant survey, namely: the level of auditory attention, soundscape complexity, sound nuisance due to objects, that due to human voices, and the ease of carrying on a discussion in the restaurant. A two-level soundscape analysis is carried out based on the feedback response of 220 students. The audio recordings of the changing restaurant soundscape are also examined for objective signal complexity changes, via first and second order entropy dynamics, in a search for tendencies that align with the subjective study. When examined at the single occupancy level, mixed trends of perceptions are observed for the general queries on auditory perceptions of attention and complexity of the restaurant soundscape. In contrast, trends, though not always monotonic, appeared when the survey subjects were queried on specific aspects such as sound nuisance due to objects, that due to human voices, and the level of ease of carrying on a discussion. Auditory complexity perceptions seem to undergo the most changes when the space occupancy transits from low to high ranges. The obtained subjective-objective results are interpreted in light of the effects of reverberation and invoked effects, particularly mechanical sound masking and the Lombard effect, during the changes of the occupancy ranges in this case study.