Abstract
Noise characteristics of bolster and balloon of two-for-one twister were investigated by analyzing the noise source of the twister. To identify the noise sources of the twister, sound intensity was measured under machine operation. In addition, frequency spectra of the sound at operator position and acceleration at the bolster area were measured along with sound intensity to help identify the noise characteristics of the two-for-one twister. The results indicate that the maximum noise level occurs along the bolster area due to the structure-borne noise, however, throughout the individual frequency analysis, balloon noise by yarn rotation causing air-borne noise becomes dominant as rotating speed gets higher. This indicates that the noise reduction of the two-for-one twister should focus on both structure-borne noise as well as airborne noise.