벽체 차음성능 측정의 신뢰성 확보를 위한 실험적 연구

Abstract

Many types of walls are being developed in order to meet the noise standards which have been strengthened recently. Verification for walls developed for meeting the standards is generally done by evaluating various performances including sound insulation performance through laboratory method, and the sound insulation performance, which is one of evaluation standards, is an important criterion for evaluating indoor noises in residence areas surrounded by walls.

Standard laboratories, in which evaluation of sound insulation of walls are made, are generally classified into an indeterminate form type and a rectangular type according to the shape of laboratories, and rectangular type laboratories are widely used recently due to the sound field characteristics similar to that of residence spaces. When experiments are performed at rectangular type laboratories, however, standing waves are generated due to the symmetric shape of indoor boundary surfaces. The standing wave generated in this environment can cause superposition of indoor sound field modes, generating deviations in sound pressure in the room, and this deviations in sound pressure in rectangular type laboratories can negatively affect the results of sound insulation performances.

In this study, research has been made on the method for reducing deviations in sound pressure which are generated at ISO type rectangular laboratories when measuring sound insulating performance of walls.

First, in order to verify the effects according to the sound absorbing power of a sound receiving room, differences in sound insulating performance were investigated for an empty reverberation room and a reverberation room with sound absorbing material installed.

Second, the positions of a speaker for advantageous forming of diffuse sound field were identified through the indoor sound pressure distribution characteristics according to the positions of the speaker.

Third, effective measuring points which are similar to average value of indoor space were identified through the indoor sound pressure distribution characteristics according to the position of the microphone.

Lastly, the effects of flanking transmission which is transmitted by the walls of the laboratory were identified.

Methods for reducing the deviation in sound pressure by controlling each of these effect factors were verified through the research, and it is proved that the undervalued sound insulation performances can be improved on the basis of the methods provided by this study.