Stimulated by market demand and technological progress, the audio industry is booming. Many high-fidelity earphones are no longer satisfactory with simply providing customers with products but tend to provide customers with more opportunities to adjust their own tuning, one of which is to add the earphones with different acoustic silencer foam. This study begins by introducing the different types of earphones and their development history. After that, the specific research content is raised by questioning the prevailing perception of acoustic silencer foam in earphones. By comparing and analyzing the differences reflected by the frequency response curves of headphones equipped with different types of acoustic silencer foam, it is concluded that the smaller the cells of acoustic silencer foam and the presence of membrane will increase its ability to reduce the loudness at high frequency. This study reveals two significant characteristics which affect the performance of acoustic silencer foam and provides a reliable theoretical basis for the tuning technology of foam.