* Corresponding authorThis study aims to explore how the soundscape quality of traffic noise environments can be improved by the masking effects of birdsong in terms of four soundscape characteristics, i.e., Perceived Loudness, Naturalness, Annoyance and Pleasantness. Four factors that may influence the masking effects of birdsong (i.e., distance of the receiver from a sound source, loudness of masker, occurrence frequencies of masker, and visibility of sound sources) were examined by listening tests. The results show that the masking effects are more significant in the road traffic noise environments with lower sound levels (e.g. <52.5 dBA), or of distance from traffic (e.g. >19 m). Adding birdsong can indeed increase the Naturalness and Pleasantness of the traffic noise environment at different distances of the receiver from a road. Naturalness, Annoyance and Pleasantness, but not Perceived Loudness, can be altered by increasing the birdsong loudness (i.e., from 37.5 to 52.5 dBA in this study). The Pleasantness of traffic noise environments increases significantly from 2.7 to 6.7, when the occurrence of birdsong over a period of 30 s is increased from 2 to 6 times. The visibility of the sound source also influences the masking effects, but its effect is not as significant as the effects of the three other factors.

Abstract:The aim of this study is to determine how to increase birdsong loudness and the visibility of green areas in low-density residential areas by controlling urban morphological parameters. The spatial sound level distributions of birdsong at 12 sites sampled from a GIS database of Assen, the Netherlands, were simulated by noise mapping techniques and calculated using a MATLAB program on spatial sound level matrices. The visibilities of green areas are analysed and calculated by Visibility Analysis Graph in Space Syntax. Correlation analyses were conducted between the obtained data on spatial sound level indices, the mean visibility and urban morphological parameters. The results show that birdsong loudness has significant positive linear relationships with urban morphological parameters, including Building Plan Area Fraction (R 2 =0.491), Green Area Perimeters (R 2

No abstract

The importance of multi-sensory perception in constructing human landscape experiences has been increasingly emphasized in contemporary urban life. The aim of this study is to explore aural-visual interaction attributes that may influence people’s perceived overall soundscape comfort in urban green spaces (UGSs). To achieve this, a total of 12 perceptive indicators were identified from the existing literature to evaluate people’s perceived visual and acoustic attributes and types of sound sources, and their relations to the perceived soundscape comfort. 268 responses were obtained in a questionnaire-based survey conducted in five UGSs in Chengdu Outer Ring Ecological Zone. This was done whilst a typical objective acoustic indicator, sound level, was used as a mediator for potential changes on these relations within different sound level ranges. Results suggested that a low level of environmental sound does not correspond to higher ratings on the overall soundscape comfort. It was also found that the environmental sound level of 77 dBA was a turning point in the relation between people’s soundscape comfort and its influential indicators in UGSs. A set of six models was then provided to describe the overall soundscape comfort and its contributing indicators in aural-visual interactions, respectively, in sound level ranges below and above 77dBA.

This study aims to explore whether and howu rban morphology influences the capability of ar esidential area on attenuating trafficn oise levels. Particular attention is paid to low-density residential areas, which are more appealing for study because of their relatively lowcapability of noise resistance compared with the high-density morphology.S ix urban morphological parameters that are accessible and commonly used in urban design and planning are selected. Noise mapping techniques have been employed and aMAT LAB program has been developed to obtain the spatial noise levelindices, L n .The relationships of urban morphological parameters with the spatial noise levela ttenuation and the size of noisy areas were subsequently revealed. The results indicate that the spatial noise levelattenuation primarily occurs on noisy façades and in noisy open areas; urban morphology influences the attenuation in open areas more than on façades. As ite with quieter open areas, as measured by average spatial noise levels, such as L 50 ,i sp rone to have as maller sized 'Less Noisy Area.'As ite that has greater building coverage, however, has noisy façades with higher spatial noise levels in terms of L 10 and L 20 . With an increase of the Building Plan Area Fraction (BPAF),the spatial noise levels on noisy building façades do not decrease butincrease continuously.The Complete Aspect Ratio (CAR)and the Building Frontal Area Index (BFAI) both have the greatest impact on the average spatial noise levels, such as L 60 in open areas. The reduction of noisy open areas occurs with ad ecrease in the distance between the first-rowb uildings and at rafficr oad. It has also been revealed that the noise reduction occurs with an increase of façade areas along aroad.