Optimizing acoustic conditions in special education classrooms: A comprehensive study of speech intelligibility for students with intellectual disabilities

Abstract

Students with intellectual disabilities often exhibit atypical sensory processing, including heightened auditory sensitivity, which can hinder their ability to comprehend verbal instructions in acoustically inadequate classrooms. Exposure to loud or abrupt sounds may also trigger behavioral challenges. This study explores design strategies to improve classroom acoustic environments and support speech intelligibility for students with intellectual disabilities. Acoustic simulations were conducted using CATT-Acoustic™ software across two classroom layouts: a common design with individual seating, and a modified layout featuring clustered seating and spatial zoning based on sensory stimulation levels. Each layout was evaluated under two material conditions: one using common finishing materials and another incorporating high-absorption acoustic treatments. Key acoustic parameters—reverberation time (RT), speech clarity (C50), and speech transmission index (STI)—were analyzed for each scenario. Results indicate that the modified layout, when combined with targeted acoustic treatments, substantially improves acoustic performance across all frequency bands and listener positions. These findings highlight the value of integrating inclusive spatial design with material strategies to enhance speech intelligibility and learning outcomes for students with cognitive and sensory challenges.