Acoustic performance of coffee waste/polylactic acid composite microperforated panels for noise control in cafe spaces

Excessive noise exposure poses significant health risks such as cognitive impairment, cardiovascular diseases, and sleep disturbances, highlighting the need for effective noise control strategies. This study examines the acoustic performance of microperforated panels made from polylactic acid (PLA) and coffee waste/PLA composite (CWPLA) using three-dimensional printing. The CWPLA panels achieved a peak sound absorption coefficient of 0.90 at 800 Hz, outperforming the PLA panels. Reverberation time (RT) analysis conducted with Odeon Acoustics Software revealed that the CWPLA panels reduced reverberation by 0.59 s at 1000 Hz with 50 % ceiling coverage, whereas the PLA panels reduced reverberation by 0.72 s at 500 Hz under similar coverage conditions. Full ceiling coverage further improved performance by reducing RT across all frequency ranges. PLA panels were more effective for low to mid frequencies, such as speech, whereas PLA panels excelled in high-frequency environments with machinery or heating, ventilation, and air conditioning systems. The enhanced performance of CWPLA panels was attributed to their increased porosity and improved internal damping provided by the integrated coffee waste fibers. Additionally, increasing the cavity depth from 10 mm to 20 mm further enhanced sound absorption by promoting Helmholtz resonance. These findings demonstrate that CWPLA panels provide effective noise control while promoting sustainability, as they support circular economic principles by converting industrial waste into high-performance materials.