Catherine Lavandier

Influence of visual setting on sound ratings in an urban environment

Abstract We assessed how listeners judgments of a set of urban sound environments were affected by co-occurring visual settings. In artificial audiovisual environments, subjects rated eight urban sound environments (recordings) when they were associated with five visual settings (four color slides varying in degree of urbanization and a control condition with no slide), along two sound scales (Unpleasant–Pleasant and Stressful–Relaxing). In general, the more urban the visual setting, the more negative the sound ratings. However, this influence depended on the type of sound. It was marked for recordings which did not include human sounds (particularly strong for bird song and weaker for traffic noise), but was absent for all recordings which included human sounds (footsteps and voices). Results are discussed in terms of the degree of matching between visual and sound information, and the degree of implication of the perceiver with these sound environments.

AMBIENT SOUND ASSESSMENT OF URBAN ENVIRONMENTS: FIELD STUDIES IN TWO FRENCH CITIES

This work aims to investigate the appraisal of typical urban soundscapes. The method consists of two simultaneous on-site procedures in various urban situations in two French cities (main thorough fares, pedestrian precincts, playgrounds and market squares). While passers-by were required to express their opinion about soundscapes through questionnaires, we recorded samples of ambient sound environments and calculated acoustic parameters. The cross analysis between survey data and acoustic parameters indicated the sound level is appropriate to the description of main thorough fares, but for similar sound level locations (square, market, or playground) two further perceptive factors were remind. The perceptual spatial dimension was correlated with acoustic indicators as background noise or standard deviation of short LAeq, whereas the temporal dimension revealed differences in the perceptual attitudes of the survey respondents. The results obtained consequently identified the limitation of matching a unique acoustic descriptor with two cognitive representations (a global point of view versus a discrete listening) of the same acoustic phenomenon.

Measurements of acoustic environments for urban soundscapes: Choice of homogeneous periods, optimization of durations, and selection of indicators

In order to minimize the duration of acoustic measurements and to characterize homogeneous areas from a temporal point of view, a series of six location measurements was carried out continuously during three months in Paris. Around fifty thousand samples of 5-min, 10-min, 15-min, 20-min, 30-min, and 1-h duration measurements were extracted for each location. Each sample is characterized by eleven energy indicators and ten event descriptors. In this paper, analysis of a crossroad location is detailed. Through hierarchical ascendant classification and artificial neural networks classification, it is shown that four homogeneous periods can be detected: two during the night, one during the day, and one transition corresponding either to the awakening or to the moment when the city falls asleep. 10-min measurements are necessary to discriminate these time periods at the crossroad location. At the end of the paper, a comparison with the other locations shows that minimum duration states in between 10 and 20 min. The homogeneous periods are connected to the human activities and depend on the location. Energy indicators such as LAeq, LA10, or LA90 and event indicators are necessary to characterize the different clusters.

Sound quality indicators for urban places in Paris cross-validated by Milan data

A specific smartphone application was developed to collect perceptive and acoustic data in Paris. About 3400 questionnaires were analyzed, regarding the global sound environment characterization, the perceived loudness of some emergent sources and the presence time ratio of sources that do not emerge from the background. Sound pressure level was recorded each second from the mobile phones microphone during a 10-min period. The aim of this study is to propose indicators of urban sound quality based on linear regressions with perceptive variables. A cross validation of the quality models extracted from Paris data was carried out by conducting the same survey in Milan. The proposed sound quality general model is correlated with the real perceived sound quality (72%). Another model without visual amenity and familiarity is 58% correlated with perceived sound quality. In order to improve the sound quality indicator, a site classification was performed by Kohonens Artificial Neural Network algorithm, and seven specific class models were developed. These specific models attribute more importance on source events and are slightly closer to the individual data than the global model. In general, the Parisian models underestimate the sound quality of Milan environments assessed by Italian people.

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 sound judgment depending on the urban visual setting

In a number of experiments carried out in the experimental psychology field, audition and vision proved to provide information which interacted each other. What about the audio–visual interactions in the city? The first aim of this research was to develop an experimental procedure involving methodological parameters best suitable to test the influence of the visual setting on the sound judgment in the complex sound environment. The second one was to apply it to various urban situations. In a series of simulation tests, participants rated some urban sound stimuli and this, under different visual conditions varying according to the degree of urbanization. An artificial audio–visual environment was specifically created. The experimental methods were based on three types, involving different structures of presentation of the audio–visual combinations. For each of them (except for the completely random one), two types of orders of presentation of both the visual and sound sequences were defined. The results fo...

Influence of sensory interactions between vision and audition on the perceptual characterization of room acoustics

Broad evidence on sensory interactions between vision and audition suggests that visual information available to listeners‐spectators in concert halls is likely to interfere in the evaluation process of the acoustical qual‐ ity. The influence of the stage visual distance on the auditory apparent distance was studied in four magnitude estimation paradigms. Sound stimuli providing successive impressions of auditory distance were generated by a virtual room acoustics processor (‘‘Spatialisateur’’) in binaural format and presented separately or coupled with 3‐D concert hall pictures. Subjects were asked to judge the auditory distance. Pilot experiments I and II obtain a first qualitative observation of the effects and study a progressive change observed at the responses. Main experiments III and IV adopt two different procedures of stimuli presentation and improved sound reproduction and attempt a first objective evaluation of the results. The analysis of variance performed on the responses reveals a small of...

Characterization of urban sound environments using a comprehensive approach combining open data, measurements, and modeling

Urban noise reduction is a societal priority. In this context, the European Directive 2002/49/EC aims at producing strategic noise maps for large cities. However, nowadays the relevance of such maps is questionable, due to considerable uncertainties, which are rarely quantified. Conversely, the development of noise observatories can provide useful information for a more realistic description of the sound environment, but at the expense of insufficient spatial resolution and high costs. Thus, the CENSE project aims at proposing a new methodology for the production of more realistic noise maps, based on an assimilation of simulated and measured data, collected through a dense network of low-cost sensors that rely on new technologies. In addition, the proposed approach tries to take into account the various sources of uncertainty, either from measurements and modeling. Beyond the production of physical indicators, the project also includes advanced sound environments characterization, through sound recognition and perceptual assessments. CENSE is resolutely a multidisciplinary project, bringing together experts from environmental acoustics, data assimilation, statistics, GIS, sensor networks, signal processing, and noise perception. As the project is in launch state, the present communication will focus on a global overview, emphasizing the innovative and key points of the project.Urban noise reduction is a societal priority. In this context, the European Directive 2002/49/EC aims at producing strategic noise maps for large cities. However, nowadays the relevance of such maps is questionable, due to considerable uncertainties, which are rarely quantified. Conversely, the development of noise observatories can provide useful information for a more realistic description of the sound environment, but at the expense of insufficient spatial resolution and high costs. Thus, the CENSE project aims at proposing a new methodology for the production of more realistic noise maps, based on an assimilation of simulated and measured data, collected through a dense network of low-cost sensors that rely on new technologies. In addition, the proposed approach tries to take into account the various sources of uncertainty, either from measurements and modeling. Beyond the production of physical indicators, the project also includes advanced sound environments characterization, through sound recogniti...

Urban soundscape maps modelled withgeo-referenced data

Abstract The noise maps that are currently proposed as part of the EU Directive are based on the calculation of the Lday, Levening and Lnight. These levels are calculated from emission and propagation models that are expensive in time. These noise maps are criticized for being distant from the perception of city users. Thus, calculation models of sound quality have been proposed, for being closer to city users’ perception. They are either based on perceptual variables, or on acoustic measurements, or on georeferenced data, the latter being often already integrated into the Geographic Information Systems of most French metropolises. Considering 89 Parisian situations, this article proposes to compare the sound quality really perceived, with those from models using geo-referenced data. It also looks at the modeling of perceptual variables that influence the sound quality, such as perceived loudness, the perceived time ratio of traffic, voices and birds. To do this, such geo-referenced data as road traffic, the presence of gardens, food shops, restaurants, bars, schools, markets, are transformed into core densities. Being quick and easy to calculate, these densities predict effectively sound quality in the urban public space. Visualization of urban soundscape maps are proposed in this paper.

Case Study: Ambient Sound Assessment of Educational Buildings

The present study is devoted to the analysis of acoustic quality of educational buildings. Three secondary schools were studied. Children were asked to draw and write how they perceived and evaluated the acoustic environment of their school. A semiotic analysis of graphics and a semantic analysis of verbal reports allow sounds to be identified as cognitive representations: they are mainly represented by sources as elements of a “context”, involving activities, time and locations. A measurement program was carried out, especially in locations where acoustic problems were mentioned. These two perceptive and physical approaches lead to the conclusion that the design process for educational buildings can be treated at different levels: a functional and an organizational level on the one hand, and a physical level on the other.