Noise is an unpleasant and unwanted sound for every human and animal. Noise can also interfere with one's communication and concentration. Nowadays, many sound absorber panels have been produced to overcome arising noise issues. A sound absorber panel works to absorb sound either in low or high frequencies. Usually, in Malaysia, synthetic materials are used for producing sound absorber panels. Glass fibre and minerals are the most common examples of synthetic materials used to produce sound absorber panels. In particular, glass fibre has a good result in sound absorption. However, it also brings negative effects to humans' health, such as skin inflammation, redness, cough, breathlessness, and others. Therefore, for this study, natural materials from recycling have been used to produce sound absorber panels, which are egg trays, papers, and plastics. The panels were tested with the impedance tube test to obtain the sound absorption coefficient (SAC) and the noise reduction coefficient (NRC). The values of sound absorption of plastics and papers are good at the frequency of 2,000 Hz (i.e., 0.75 and 0.74, respectively). However, the value of SAC for papers increased to 0.86, compared to the value of SAC for plastics that decreased to 0.67. Furthermore, the value of NRC for papers is better than plastics. Next, the reverberation room test was also performed on the panels to obtain the echo time value (RT) in the current unit. The comparison of echo time for this test is between the values for a room with and without panels. The results from the test showed that the value of echo time for the room with the panels is better than the room without panels.
