A Scoping Review of Noise Transmission from Outdoors into Classrooms: Factors, Impacts and Mitigation Strategies

Effective communication between teachers and students is vital for successful learning, but outdoor noise can disrupt classroom acoustics and hinder this process. Despite growing research on classroom acoustics, gaps remain in understanding how factors like environmental noise, building design, and classroom acoustics interact to affect learning environments. This scoping review aims to systematically synthesize existing literature on the transmission of outdoor noise into classrooms. It explores the sources and factors that contribute to noise transmission, examines how the classroom acoustic properties that influence the impact of transmitted noise on occupants, and reviews effective mitigation strategies. The review analysed 33 peer-reviewed papers from 2003 to 2023, retrieved from Web of Science and Science Direct using the keywords Classroom acoustics AND Outdoor noise. Included studies that met criteria such as focusing on outdoor noise in mainstream classrooms and being published in English peer-reviewed journals. Traffic, aircraft, and railway noise were identified as major sources, with traffic peaking in the morning and afternoon. Building design, façade insulation, and ventilation influenced noise transmission exacerbated by proximity to noise sources. Poor acoustic properties like high reverberation time reduce speech clarity and increase background noise, affecting students' cognitive performance and teachers' vocal health. Mitigating strategies for noise include improved façade insulation, noise barriers, and window placement. This review also identifies gaps in current research, particularly regarding the combined effects of architectural elements such as building shape, height, and façade ratio. Future studies should explore how these factors interact to develop more effective noise management strategies in school. Implementing these strategies will enhance classroom acoustics, benefiting its occupants.