Investigation of acoustical climate in the shadow zones of noise barriers

Abstract

Acoustic noise is attributed to one of the main stressors negatively influencing human life quality. Long lasting noise effect has detrimental effects on humans and can be described as having toxic consequences, such as disturbed constitutional effects and annoyance. These questions are of common interest in agglomerations which are located near highways in suburbs, where the traffic flow is intensive. Constantly intensifying transport flows in highways radiates noise which is believed will increase by 2…3 dB until the year 2015. This clearly shows that the area polluted by noise is going to increase under the dependence 10·lg R, which indicates that it will approximately double. One of the technical solutions for the reduction of noise is the installation of lightweight acoustic barriers between the noise source (highway) and the area which is being protected. Together with the attenuation effect, acoustic barriers or earth berms significantly distorts the amplitude frequency characteristic of noise which leads to the changes of acoustical comfort. The aim of this work was to investigate the acoustic climate in the barrier shelterbelt. Acoustical climate was assessed using the data which was adopted by measuring sound pressure levels in the various distances perpendicularly and longitudinally the acoustic barrier. Several metrics, such as speech interference level (SIL), quality assessment index (QAI) and psychoacoustic sharpness were used as indicators of acoustic comfort. It was found that acoustic climate in the shadow zone of lightweight barrier was poor according to above mentioned measures. It was concluded, that psychoacoustic measure of sharpness is a better indicate of acoustical climate in near distances while QAI – further from barrier.