Francesco Aletta

The influence of visual characteristics of barriers on railway noise perception.

Noise annoyance is considered as the main effect of noise, it is a complex and multifaceted psychological concept dealing with immediate behavioral and evaluative aspects. In the last decades the research has intensely investigated the correlation between noise exposure and noise annoyance, nevertheless recent studies confirm that non-auditory factors influence the noise perception of individuals. In particular audio-video interaction can play a fundamental role. Today Immersive Virtual Reality (IVR) systems allow building laboratory test providing realistic experiences of the surrounding environment to detect more accurate information about the reactions of the local population. Regarding the interventions for environmental noise control the barriers represent the main solution; however some aspects related to their visual characteristic have to be further investigated. This paper presented a case study, where a sample of residents living close to a railway line assessed noise-related aspects for several barriers with different visual characteristics in an IVR laboratory test. In particular, three main factors were analyzed: the barrier type concerning the visibility of the noise source through the screen, the visual aspect of the barrier concerning some aesthetic issues and the noise level at the receiver concerning the acoustic performance of the barrier and the magnitude of the sound source. The main results of the ANOVA analysis showed that for transparent barriers Perceived Loudness and Noise Annoyance were judged lower than for opaque barriers; this difference increased as noise level increased.

The Effects of Vision-Related Aspects on Noise Perception of Wind Turbines in Quiet Areas

Preserving the soundscape and geographic extension of quiet areas is a great challenge against the wide-spreading of environmental noise. The E.U. Environmental Noise Directive underlines the need to preserve quiet areas as a new aim for the management of noise in European countries. At the same time, due to their low population density, rural areas characterized by suitable wind are considered appropriate locations for installing wind farms. However, despite the fact that wind farms are represented as environmentally friendly projects, these plants are often viewed as visual and audible intruders, that spoil the landscape and generate noise. Even though the correlations are still unclear, it is obvious that visual impacts of wind farms could increase due to their size and coherence with respect to the rural/quiet environment. In this paper, by using the Immersive Virtual Reality technique, some visual and acoustical aspects of the impact of a wind farm on a sample of subjects were assessed and analyzed. The subjects were immersed in a virtual scenario that represented a situation of a typical rural outdoor scenario that they experienced at different distances from the wind turbines. The influence of the number and the colour of wind turbines on global, visual and auditory judgment were investigated. The main results showed that, regarding the number of wind turbines, the visual component has a weak effect on individual reactions, while the colour influences both visual and auditory individual reactions, although in a different way.

Chatty maps: Constructing sound maps of urban areas from social media data

Urban sound has a huge influence over how we perceive places. Yet, city planning is concerned mainly with noise, simply because annoying sounds come to the attention of city officials in the form of complaints, whereas general urban sounds do not come to the attention as they cannot be easily captured at city scale. To capture both unpleasant and pleasant sounds, we applied a new methodology that relies on tagging information of georeferenced pictures to the cities of London and Barcelona. To begin with, we compiled the first urban sound dictionary and compared it with the one produced by collating insights from the literature: ours was experimentally more valid (if correlated with official noise pollution levels) and offered a wider geographical coverage. From picture tags, we then studied the relationship between soundscapes and emotions. We learned that streets with music sounds were associated with strong emotions of joy or sadness, whereas those with human sounds were associated with joy or surprise. Finally, we studied the relationship between soundscapes and peoples perceptions and, in so doing, we were able to map which areas are chaotic, monotonous, calm and exciting. Those insights promise to inform the creation of restorative experiences in our increasingly urbanized world.

Towards the integration of urban sound planning in urban development processes: the study of four test sites within the SONORUS project

Abstract Noise pollution in urban environments is today a major problem affecting inhabitants of many European cities. Reducing noise is therefore a necessity. As a result, many cities now have noise action plans comprising concrete actions to tackle noise issues in affected areas. Nevertheless, these often isolated documents only address existing problems. In order to change this practice an integrated strategy is necessary. A new approach to urban sound planning, a holistic approach, is being developed and tested within the SONORUS project and it is described in this paper. SONORUS, the Urban Sound Planner project, is an initial training network (ITN) that is educating researchers in a whole range of acoustic disciplines, as well as in advanced urban planning processes. An essential part of this training is the application of the holistic approach to real test sites. Although this is an ongoing work, a few innovative techniques were already developed and its application to the test sites resulted in improved urban sound planning tools. This paper promotes the discussion about the implications that the holistic approach might have in urban sound planning policies and how it can be a driving force for changing the noise pollution situation in urban environments.

The effect of walking sounds from different walked-on materials on the soundscape of urban parks

Urban parks are essential environmental resources in contemporary cities, for the substantial social and psychological relief they provide for local communities. In recent years, the potential of the soundscape approach for enhancing the ecological contribution of such environmental assets has been intensely investigated. Although, researchers tended to focus on the perception of people “staying” in the park, whilst it is important to consider how the sonic environment would be dynamically perceived by users walking across the park. Within this framework, the present study aimed to investigate the effect of different footpath materials on soundscape quality and walking quality perception for people walking in an urban park, considering that the experience of such users is affected by both the background acoustic environment of the park and their walking sound. To this purpose, a laboratory experiment was carried out with 25 participants. Four different walked-on materials that are likely to be used in urban parks were tested: grass, wood, stone and gravel. Results show that the material factor has a significant effect on both auditory and haptic perception. Furthermore, positive correlations can be observed between auditory and haptic variables, confirming that the soundscape appreciation for people walking in urban parks is likely to be affected also by other but aural sensory modalities. The paper ultimately points out that it is possible to re-think the approach to urban parks design and more specifically to the footpaths and the walking sounds that their materials are likely to produce.

The effect of vision on the perception of the noise produced by a chiller in a common living environment

Over the years, different noise sources related to community noise and their potential for eliciting noise annoyance have been investigated. Despite being a very common source within the urban realm, there is a current lack of literature on the perception of noise produced by small-medium sized sources like chillers and air conditioning devices. There are relatively few studies on the influence of audiovisual factors on noise perception for such sources. The main aim of this paper was to investigate the influence of the visibility of a chiller on perceived loudness and self-reported annoyance in a common indoor environment. Furthermore, this research aimed to investigate whether the abovementioned effects persisted in the presence of a cognitive task. To this purpose, two laboratory experiments were performed by means of an immersive virtual reality (IVR) system. Results show that the distance of the chiller influenced the noise perception, while the visibility of the chiller itself does not, assuming that a visual reference context is provided. Regarding the cognitive task, it was found to reduce the mean individual ratings of both the perceived loudness and noise annoyance related to the chiller, signifying that for the investigated sound source characterized by small spectral and temporal variation, it might have inhibited the attentional listening. These findings suggest that there is room for the implementation of recommendations for the design and management of such sources in the increasingly dense built environment.

Towards acoustic indicators for soundscape design

Scientific research on how people perceive, experience or understand the acoustic environment as a whole (i.e., soundscape) is still in development, both with regards to acoustic properties, as wel ...

Dimensions Underlying the Perceived Similarity of Acoustic Environments

Scientific research on how people perceive or experience and/or understand the acoustic environment as a whole (i.e., soundscape) is still in development. In order to predict how people would perceive an acoustic environment, it is central to identify its underlying acoustic properties. This was the purpose of the present study. Three successive experiments were conducted. With the aid of 30 university students, the first experiment mapped the underlying dimensions of perceived similarity among 50 acoustic environments, using a visual sorting task of their spectrograms. Three dimensions were identified: (1) Distinguishable–Indistinguishable sound sources, (2) Background–Foreground sounds, and (3) Intrusive–Smooth sound sources. The second experiment was aimed to validate the results from Experiment 1 by a listening experiment. However, a majority of the 10 expert listeners involved in Experiment 2 used a qualitatively different approach than the 30 university students in Experiment 1. A third experiment was conducted in which 10 more expert listeners performed the same task as per Experiment 2, with spliced audio signals. Nevertheless, Experiment 3 provided a statistically significantly worse result than Experiment 2. These results suggest that information about the meaning of the recorded sounds could be retrieved in the spectrograms, and that the meaning of the sounds may be captured with the aid of holistic features of the acoustic environment, but such features are still unexplored and further in-depth research is needed in this field.

A soundscape approach to exploring design strategies for acoustic comfort in modern public libraries: a case study of the Library of Birmingham

Abstract Taking the soundscape approach to a study of the Library of Birmingham, this paper explored acoustic comfort in modern public libraries and measured the quality of the perceived sound environment, focusing on the appropriateness of the spatial organisation to facilitate users’ activities of reading and writing. The research involved four groups of participants taking soundwalks which provided data at four main floors in the Library, identifying types of sounds, measuring sound pressure levels and evaluating the overall quality and appropriateness of perceived sound environment. A human sound dominated sound environment was found in the studied case. The overall soundscape quality varied among different levels and different functional spaces. However, the results showed that the overall soundscape quality of each floor varied and was not necessarily determined by the overall appropriateness and sound pressure level. The participants in the study were found influenced by their soundscape cognitions of spaces through visual and acoustic perceptions, as well as by their purposes of using the space. From these results, the layout of spaces is suggested as a determining factor of acoustic comfort, and design strategies were discussed to achieve acoustic comfort in modern public libraries.

Influence of Personal Factors on Sound Perception and Overall Experience in Urban Green Areas. A Case Study of a Cycling Path Highly Exposed to Road Traffic Noise

In contemporary urban design, green public areas play a vital role. They have great societal value, but if exposed to undue environmental noise their restorative potential might be compromised. On the other hand, research has shown that the presence of greenery can moderate noise annoyance in areas with high sound levels, while personal factors are expected to play an important role too. A cycling path bordered by vegetation, but highly exposed to road traffic noise, was here considered as a case study. A sound perception survey was submitted to participants on site and they were subsequently sorted into groups according to their noise sensitivity, visual attention and attitude towards greenery. The aim of this study was testing whether these three personal factors could affect their noise perception and overall experience of the place. Results showed that people highly sensitive to noise and more sceptical towards greenery’s potential as an environmental moderator reported worse soundscape quality, while visually attentive people reported better quality. These three personal factors were found to be statistically independent. This study shows that several person-related factors impact the assessment of the sound environment in green areas. Although the majority of the respondents benefit from the presence of visual green, policy-makers and planners should be aware that for a significant subset of the population, it should be accompanied by a tranquil soundscape to be fully appreciated.