Complexity and mismatch: Comparing perception of acoustic and visual environments in the high-density city

Abstract

Negative mood, especially mental stress, can lead to a variety of severe health problems, such as cardiovascular diseases, stroke, diabetes, suicide, etc. In high­density cities, citizens often experience a wide variety of juxtaposition of acoustic and visual environments. Compare to low­density urban areas, suburban, and rural areas, high­density cities provide a highly diverse, and often strange combinations of acoustic and visual environments. Previous studies reported green landscapes and natural sounds can promote positive mood and reduce stress. However, we don’t know to what extent different combinations of acoustic and visual environments in the high­density city will have different effects on mood and stress. In a virtual reality lab, each of 228 participants was randomly assigned to one out of 19 acoustic­visual environments after a 13­ min stressful mental task (Trier Social Stress Test). Each condition had six female and six male participants. Each environment was a 10­minute 3D video or audio, which is a combination of one of four types of visual environments (urban street, office plaza, green park, no vision content) and one of five types of acoustic environments (No sound, traffic sound dominated, mechanical sound dominated, natural sound dominated, natural sound). During the experiment, a participant filled out three State­Trait Anxiety Inventory (STAI) questionnaire to report changes of mood status. The participant's Skin Conductance and Blood Volume Pulse, which are physiological indicators of mental stress status, were measured. At last, the participants wrote a narrative to report her or his mental status as they are exposure to the assigned stimulation. All visual and acoustic materials were collected and produced in Hong Kong. Results suggest that visual and acoustic environments work together on influencing peoples’ mood and stress status. The acoustic environment adds significant impacts on mood and stress status. The mismatch of acoustic and visual environment often cause an adverse impact on mood and stress status. The positive impact of green landscapes was largely weakened by traffic noise. Last, the combination of green landscape and natural sound has the greatest positive effect.