Although one of the most harmful factors to health is noise, it is often ignored in life cycle assessment (LCA) studies. Most researches regarding noise inclusion in LCA focus on the problem of transport noise, and very few works consider the impact of noise emitted by other sources. This study addresses the effects of noise generated by cogeneration plants. The main objective is to assess the environmental performance of the noise reduction system by considering the health effects of noise due to steam discharge as well as to compare the environmental loss associated with the production and disposal of a steam silencer with the benefits resulting from its application for noise reduction. A method to determine midpoint and endpoint human health indicators for a composition of noise emitted by intermittent stationary source and background noise is developed. The results indicate that the health benefit due to noise reduction is six orders of magnitude greater than the environmental loss. Human health indicators attributable to noise reduction in the residential zones under consideration span a wide range of disability adjusted life years (DALY)—0.16–136 DALY. The greatest values occur in the densely populated areas located close to the noise source. A formula is proposed to express annoyance of the residents of individual zones depending on their distance to the steam discharge source, its sound power level, and existing background noise level. Uncertainty and sensitivity analyses have been carried out assuming other conditions. Modifications of sound power level, noise reduction efficiency, steam discharge duration, and the silencer lifetime have not affected the overall conclusion drawn.

The primary goal of this research was to study transmission loss and absorption of fluted PVC panels using experimental and theoretical methods. During these studies, the link between panel size, thickness, transmission loss, and absorption was considered. We measured the transmission loss and absorption in reverberation rooms according to ISO standards. Hansen’s theoretical model was also used to predict the transmission loss. Agreement between TL prediction according to Hansen’s model and measured results for some of the studied panels were observed. However, the analytical prediction, according to Hansen’s model, for heavy fluted PVC panels must be used with caution. The absorption properties of the studied fluted PVC panels are also connected with their resonance, and, in addition, the resonance frequency is associated with the space between the ribs and wave propagation in the panel’s plane.

In the comment of Heijungs and Cucurachi [...]

Authors present a study on transmission loss and absorption of corrugated PVC panels. Tests were conducted in reverberation room and it has been proven, both theoretically and experimentally, that there is a relationship between the panel type and its transmission loss and absorption. Panel size and thickness was also taken into consideration during testing procedure. Analyses also show that the Hansen model was not perfectly accurate when predicting the transmission loss for some of the tested samples.

This paper presents the aeroacoustics result of the trailing edge noise prepared wings two species of owl - Barn owl (Tyto alba), called “good hearing” and Northern hawk-owl (Surnia ulula), called “good seeing”. The acoustic performance comparisons between the Barn owl and Northern hawk-owl show that there are differences between the sound intensity the studied wings. These results prove that the special sound suppression characteristics of wing feather play an important role for their silent flight. Therefore the flat plates with the cutting trailing edge have been studied. At lower speeds, a better noise reduction effect was obtained for the plates with edges as elliptical arcs. On the basis of the above tests it can be concluded that other types of notches on the trailing edge (not just a sawtooth) also reduce the aerodynamic noise of flat plate.