Study of Acoustic Properties and Noise Levels in Selected Public Secondary Schools in Onitsha, Anambra State

Background: Excessive noise in school environments impairs concentration, learning outcomes, and teacher vocal health. Systematic acoustic characterisation of secondary school classrooms in Nigerian urban settings is lacking. Aim: This study investigated acoustic properties and ambient noise levels in selected public secondary school classrooms in Onitsha, Anambra State, South East Nigeria. Methods: Sound level measurements were conducted in 20 classrooms across five secondary schools using a calibrated Class 2 sound level meter. Reverberation time was measured using the interrupted noise source method. External noise sources were identified through spectral analysis. Results: Mean ambient noise levels during teaching hours ranged from 62 to 79 dB(A), significantly above the WHO recommended 35 dB(A) for classrooms. Reverberation times ranged from 0.8 to 2.1 seconds, with bare concrete rooms exhibiting the highest values. Road traffic and marketplace noise were the dominant external sources. Conclusion: Noise pollution in Onitsha secondary school classrooms is at levels detrimental to learning. Recommendations include installation of sound-absorbing wall panels, tree planting as external noise barriers, and window double-glazing where feasible. Keywords: acoustics, noise levels, secondary schools, Onitsha, reverberation time.