In recent years, noise has become a serious hazard and can have permanent biological and psychological effects on humans and other organisms in nature. Textile materials are commonly used as absorbent acoustic materials for noise reduction. This work examines the use of electrospun nylon-6 and polyurethane nanofibres (PU NFs) to improve the sound absorption and sound insulation properties of polyurethane foam. In this work, nylon-6 and polyurethane nanofibres were prepared by an electrospinning technique and were glued to a polyurethane foam. The sound absorption coefficient of the materials was measured by the impedance tube method. An impedance tube was used to measure the sound absorption and airborne sound insulation. The results showed decreased sound absorption properties, whereas the sound insulation was highly enhanced when polyurethane/nanofibre hybrids were used, as compared to the pristine polyurethane foam. Furthermore, the sound insulation properties of polyurethane foam were highly enhanced when the foam was combined with nylon-6 NFs, compared with the polyurethane foam with PU NFs. Therefore, by investigating the acoustic characteristics of electrospun nylon-6 and PU nanofibres, we believe that this study can broaden the application of electrospun nanofibres for sound pollution control.

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In the previous test, the verification of the standard floor impact source was carried out comparing the physical characteristics with living impact sources. The result was appeared the validation of the standard impact source was very low because of differences of physical characteristics. This study aims to evaluate annoyance and loudness of standard impact source which is used for the measurement of floor impact sound, and to compare the annoyance and loudness of living impact sources which are produced in real life. The impact sources considered are tapping machine, tire and impact ball as standard sources, and nine real sources which were chosen from the existing researches. The result showed differences of annoyance and loudness between standard impact sources and living impact sources, which means the standard impact sources may rate the performance of floor system inappropriately. In the future, the rating method should be examined how the standard impact sources are similar with real sources in the point of rating the performance of floor system.

This study examined the relationship between noise annoyance and sound pressure levels in indoor environments due to various modes of transportation including road traffic, railways, and aircraft. The experiments were conducted in a laboratory environment, where the limited sense of presence was overcome by using an appropriate exposure duration. The degree of annoyance was surveyed and the average score was converted into percent of annoyance (%PA) and percent high annoyance (%HA) values among respondents for comparisons with the noise levels. As expected, the subjective response increased in proportion with the noise level and there was an extremely high correlation. Notably, the smallest deviation in responses was found for road traffic noise. Overall, the noise levels corresponding to a %PA of 50% were 41 dB(A), 48 dB(A), and 49 dB(A) for road traffic noise, railway noise, and aircraft noise, respectively. In addition, the levels corresponding to a %HA of 20% were 45 dB(A), 51 dB(A), and 53 dB(A), respectively. The %HA values coincided well with current regulations for indoor noise in Korea (45 dB(A)).