Zhu and teammates found that “Listening to natural sounds, both live and recorded, in either a natural or built environment is considered natural sound exposure (NSE). . . . Fifteen studies . . . were selected for [a] meta-analysis. . . . results indicate that NSE has certain positive effects: (a) In terms of emotional changes, NSE significantly reduces anxiety. . . . (b) In terms of physiological reaction, NSE resulted in reduced heart rate (HR) . . . systolic…