Application of a TiO2 nanocomposite in earplugs: a case study of noise reduction.

Background. Use of hearing protection devices has become necessary when other control measures cannot reduce noise to a safe and standard level. In most countries, more effective hearing protection devices are in demand. Objective. The aim of this study was to examine the effects of titanium dioxide (TiO2) nanoparticles on noise reduction efficiency in a polyvinyl chloride (PVC) earplug. Methods. An S-60 type PVC polymer as the main matrix and TiO2 of 30-nm size were used. The PVC/TiO2 nanocomposite was mixed at a temperature of 160 °C and 40 rpm and the samples were prepared with 0, 0.2 and 0.5 wt% of TiO2 nanoparticle concentrations. Results. Earplug samples with PVC/TiO2 (0.2, 0.5 wt%) nanoparticles, when compared with raw earplugs, showed almost equal noise attenuation at low frequencies (500-125 Hz). However, at high frequencies (2-8 kHz), the power of noise reduction for earplugs containing TiO2 nanoparticles was significantly increased. Conclusions. The results of the present study showed that samples containing nanoparticles of TiO2 had more noticeable noise reduction abilities at higher frequencies in comparison with samples without the nanoparticles.