Understanding urban and natural soundscapes

The concept of soundscape has garnered increasing research attention over the last decade for studying and designing the sonic environment of public spaces. It is therefore critical to advance knowledge on how the soundscape of a place is evoked by its sonic environment, given visual, cultural, and situational contexts. Working Group 1 of the COST action "Soundscapes of European cities and landscapes" revolves around this question. In our current understanding the sounds that are heard during normal activities in a place trigger meaning and emotions based on the matching with expectations of the people using and acting in that place. This complete package of human experience in relation to the sonic environment can be named the soundscape. In terms of design, this understanding opens several opportunities. The designer can decide which sounds should be heard and try to make this happen by guiding the attention to particular sounds or simply remove, add or shape sounds. In doing so, he or she should keep in mind expectations of the local users. Expectations and meaning might be changed by suitable design of non-sonic features of the environment including besides the obvious visual context also the openness, lighting, local climate, etc. Bringing these concepts to practice requires new tools and methodologies.Peer reviewe

Sound pleasantness evaluation of pedestrian walks in urban sound environments

ICA 2016, 22nd International Congress on Acoustics, BUENOS AIRES, ARGENTINE, 05-/09/2016 - 09/09/2016The health benefits of a daily physical activity, and of walking in particular, are widely acknowledged. However, walking in urban environment inevitably leads to an increased exposure to noise, which forms a drawback of choosing this transportation mode. Being able to estimate the sound pleasantness associated with an urban walk trip has many potential applications, such as informing pedestrians about the sound along their intended walk, which may help them to optimize their route choice. In the past decade, various studies have focused on characterizing and estimating the sound pleasantness perceived at specific locations, on the basis of perceptive and physical measurements. However, to estimate the sound pleasantness along an urban walking trip, an additional step is required, which consists of assessing how a pedestrian evaluates the overall pleasantness of a sound environment that varies along the walking trip. In this work, the results of two laboratory experiments and one field experiment are discussed, which were designed to assess the overall evaluation of the sound environment along an urban walk. Physical and perceptive measurements at specified positions or continuously along a series of tested routes are available, in addition to a global evaluation of the route. A comparison between the results of the three experiments provides a rich source of information to understand how the sound pleasantness of a pedestrian walk is evaluated. The main conclusion is that for short walks (of about 1 minute), a recency effect is observed, which tends to disappear when the duration of the walk increases

Comparison of noise indicators in an urban context

Inter-Noise 2016, 45th International Congress and Exposition of Noise Control Engineering, HAMBOURG, ALLEMAGNE, 21-/08/2016 - 24/08/2016Noise is a major environmental issue, which gave birth in the last decades to the development of many engineering methods dedicated to both its estimation and mitigation. The specificity of the noise pollution problem lies in the complexity of human hearing and subjective assessment, and in the high spatiotemporal variation and rich spectral content of the noise generated by a wide variety of sources in urban context. Indicators that encompass all these dimensions are required for the description of sound environments and for the evaluation of noise mitigation strategies. This paper compares usual and more specific indicators, dedicated to environmental noise analyses, by means of a literature review. The comparison is based on the three following criteria: i) the ability of indicators to describe and physically categorize the urban sound environments, ii) the relevance of indicators for describing the perceptive appreciations of urban sound environments, iii) the ability of indicators to be estimated through classical or more advanced traffic noise estimation models. A discussion compares the pro and cons of the selected indicators in an operational scop

Influence of experimental conditions on sound pleasantness evaluations

ICA 2016, 22nd International Congress on Acoustics, BUENOS AIRES, ARGENTINE, 05-/09/2016 - 09/09/2016Being able to characterize and estimate the urban sound perception is a key point to improve the city dwellers environmental quality. In the past decade, various studies have focused on collecting perceived global sound pleasantness at specific locations. Some of them were carried out on field in order to evaluate the soundscape perception of the participants directly in their context. Other studies were realized in laboratory to better control the stimuli and to increase the number of participants who were subjected to the same sound environment. Most of the laboratory experiments are done in large or semi-anechoic chamber with calibrated and highly realistic audio reproduction in order to respect the ecological validity of the experiment. On one hand, even with a high immersive level, the laboratory context is not as rich as the field context and the two types of experiment could lead to different results. On the other hand, few studies exist showing the influence of decreasing ecological validity for the same experience. This work presents a short statistical analysis of perceptive evaluations of ten urban locations under 4 different test conditions. First, evaluations are carried out directly in-situ in the city of Paris. Then audio-visual recordings of these locations are evaluated in three different experimental conditions: (i) in a well-controlled acoustic laboratory in Paris region with French people, (ii) in an acoustic laboratory in Buenos Aires with Argentinean participants and lowest immersive conditions, (iii) in a habitational room with Argentinean participants and subjective calibration. The study reveals that both the 'country' factor and the experimental conditions in laboratory do not show any significant impact on the perceived sound pleasantness and perceived loudness assessments

Data mining on urban sound sensor networks

ICA 2016, 22nd International Congress on Acoustics, BUENOS AIRES, ARGENTINE, 05-/09/2016 - 09/09/2016Urban sound sensor networks deliver megabytes of data on a daily basis so the question on how to extract useful knowledge from this overwhelming dataset is eminent. This paper presents and compares two extremely different approaches. The first approach uses as much as possible expert knowledge on how people perceive the sonic environment, the second approach simply considers the spectra obtained every time step as meaningless numbers yet tries to structure them in a meaningful way. The approach based on expert knowledge starts by extracting features that a human listener might use to detect salient sounds and to recognize these sounds. These features are then fed to a recurrent neural network that learns in an unsupervised way to structure and group these features based on co-occurrence and typical sequences. The network is constructed to mimic human auditory processing and includes inhibition and adaptation processes. The outcome of this network is the activation of a set of several hundred neurons. The second approach collects a sequence of one minute of sound spectra (1/8 second time step) and summarizes it using Gaussian mixture models in the frequency-amplitude space. Mean and standard deviation of the set of Gaussians are used for further analysis. In both cases, the outcome is clustered to analyze similarities over space and time as well as to detect outliers. Both approaches are applied on a dataset obtained from 25 measurement nodes during approximately one and a half year in Paris, France. Although the approach based on human listening models is expected to be much more precise when it comes to analyzing and clustering soundscapes, it is also much slower than the blind data analysis

Modelling of natural convection flows with large temperature differences : a benchmark problem for low Mach number solvers. Part 1, Reference solutions

There are very few reference solutions in the literature on non-Boussinesq natural convection flows. We propose here a test case problem which extends the well-known De Vahl Davis differentially heated square cavity problem to the case of large temperature differences for which the Boussinesq approximation is no longer valid. The paper is split in two parts: in this first part, we propose as yet unpublished reference solutions for cases characterized by a non-dimensional temperature difference of 0.6, (constant property and variable property cases) and (variable property case). These reference solutions were produced after a first international workshop organized by CEA and LIMSI in January 2000, in which the above authors volunteered to produce accurate numerical solutions from which the present reference solutions could be established

Activity interference caused by traffic noise: experimental determination and modeling of the number of noticed sound events

Activity interference is widely considered to be a central mechanism linking exposure to noise and emergence of annoyance. Salient sound events in particular may divert attention from the task at hand, thereby reducing task performance. Sound events caused by traffic noise intruding the dwelling are therefore often found to be a main cause of community noise annoyance. In this work, experimental and simulation results on activity interference caused by traffic noise are compared. On the one hand, an experiment on activity interference by traffic noise was conducted in a realistic setting resembling an at-home situation. Subjects were instructed to read, while being exposed to a combination of road and railway traffic noise. The number of train pass-by events, the distance to the railway track and the emergence of train events above the background noise was varied among subjects. After completion of the reading task, the subjects had to evaluate their perceived disturbance due to passing trains and to report how many trains they noticed in retrospective. On the other hand, a computational model of auditory attention was used to determine the number of train pass-by events that subjects would notice, solely based on the acoustic stimuli used in the perception experiment. Using an optimized stochastic function that simulates the attention spend on the reading activity of the subjects, the model was able to replicate trends found in the empirical results, and estimated the number of noticed train events quite well

A Relook at Canada’s Western Canada Sedimentary Basin for Power Generation and Direct-Use Energy Production

The Alberta No. 1 Project, under the terms of Canada’s Federal government’s Emerging Renewable Power Program (ERPP), must produce 5MWe net. The goal of this study was to identify areas where three essential constraining conditions overlap; (1) the temperature gradient is sufficiently high that 120°C brines at depths of 4,500m or less are potentially available, (2) there are formations at the depths targeted with known high fluid flows, and (3) there is adequate existing infrastructure that supports low-cost power grid connection as well as a direct use application. A fluid temperature of at least 120oC is needed to profitably operate the plant. Temperatures below this require increasingly greater amount of fluids to be pumped and injected making them uneconomic. Three hundred liters per second (l/sec) of 120oC water is required to generate 5 MW net of electrical power with an Organic Rankin Cycle (ORC) binary plant. A depth cut off from a project economics perspective is about 4,500m for large diameter geothermal wells. Fortunately, these formations don’t need to be thick to supply these volumes of water to the well bore and thin permeable formations are expected to be laterally extensive in the regional layer cake (Western Canada Sedimentary Basin, WCSB) geology of Alberta. Thus, targeting known high fluid producing geologic units, rather than narrow faults is an important aspect of developing a geothermal project in the WCSB. Alberta No. 1 identified nine study areas to assess for geothermal potential. Of these, the Tri-Municipal Industrial Park (south of Grande Prairie) was determined to be the most suitable for both power production and development, followed by Edson (west-central Alberta). Other areas were identified as being most suitable for basement EGS to produce power, as well as direct use from shallower formations