Measuring soundscape quality of urban environments using physiological indicators: Construction of physiological assessment dimensions and comparison with subjective dimensions

Abstract

Residents and designers typically pursue healthy urban acoustic environments. The soundscape community has established internationally recommended standards for subjective questionnaires to evaluate soundscape quality; however, much work is still needed to standardise physiological assessments. This study measures the physiological responses and subjective evaluations of participants in 20 common sound sources (scenarios) in urban public open spaces, and discusses the potential dimensions when assessing the quality of urban soundscapes through physiological indicators. Categorical principal components analysis are employed to reduce the dimensionality of the physiological data. The results indicate that physiological Dimension 1 represents the Natural–Artificial dimension, and physiological Dimension 2 potentially represents the Regular–Irregular dimension, providing a rough estimate of regularity or predictability in soundscapes. Subjective data are used as a control for physiological data, subjective Dimension 1 can be summarised as the Calm (Pleasant)–Chaotic (Annoying) dimension, whereas subjective Dimension 2 can be summarised as Familiar (Congruent)–Unfamiliar (Incongruent). Through comparing and discussing the distributions in physiological and subjective models under different sound sources, it is found that both physiologically and subjectively, the foremost dimension (Dimension 1) represents comfort and pleasure, and natural sounds can be distinctly differentiated from noise through this dimension. Although its physiological significance is not clear, the two-dimensional physiological indicator model reveals distinctions between sound sources of various categories. These findings have implications for the planning and design of liveable and comfortable urban environments from the perspective of physiological indicators.