Performance Evaluation of Multi-layer Barriers for Machine-Induced Low-Frequency Noise Attenuation

In this work, the performance of different multi-layer barrier constructions in attenuating noise has been studied experimentally. Machine-induced low-frequency noise within the frequency range of 100–500 Hz is focused in this work. Six different multi-layer barrier constructions have been employed for this purpose. Wood has been used as the rigid, reflective layer while glass wool and PE foam has been used as the soft, absorbing layers. An enclosure with five fixed walls and one flexible wall containing the noise barrier has been constructed to perform the experiments. A CASELLA CEL-62X Sound Pressure Level meter has been used to measure sound pressure at different frequencies. Results indicate that the transmission losses are not higher than 18 dB for the frequency range of interest. Results also reveal that triple-layer wooden barrier has superior performance in attenuating low-frequency noise although sandwich barriers are more suitable for higher frequencies.