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Current building standards recommend specific unoccupied background noise levels and reverberation times for classroom spaces. While clear communication in elementary school classrooms may be critical for successful learning environments, the existing research does not show a consistent connection between the classroom acoustics parameters specified in building standards and student achievement. This research seeks to determine what acoustical conditions should be attained in elementary school classrooms to optimize student achievement.
In this dissertation, acoustical studies in two midwestern United States public school systems are described. Unoccupied background noise level (BNL) and reverberation time (RT) measurements were gathered in a range of elementary school classrooms (125 total). Additionally, detailed binaural room impulse response (BRIR) measurements were gathered in 24 of these classrooms. For the BRIR measurements, a source loudspeaker with a directivity pattern similar to that of a human talker was used. The loudspeaker was placed at the front of each room at varying rotation angles to simulate a teacher facing different directions while speaking to the class. Multiple receiver positions at typical student locations were used in each classroom. The metrics calculated from the BRIR measurements include perception-based parameters, such as speech transmission index (STI), distortion of frequency-smoothed magnitude (DFSM), interaural cross-correlation (IACC), and interaural level difference (ILD).
The results from this research suggest that elementary student reading and language subject areas may be negatively impacted by higher unoccupied BNLs. Also, classrooms with lower DFSMs generally had students with higher language achievement scores. However, the classrooms included in the study had a limited range of RTs. Therefore, further investigations are needed in classrooms with longer RTs to fully assess the relationships between classroom acoustical conditions and student achievement.
Advisor: Lily M. Wang