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

Abstract

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 phone's 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 Kohonen's 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.

Modeling Soundscape Pleasantness Using perceptual Assessments and Acoustic Measurements Along Paths in Urban Context

“…In that line, the notion of perceived pleasantness proved particularly relevant to assess the quality of sound environments, and thus receives increasing attention [2], [13]- [15]. Consequently, recent models aimed to predict the pleasantness of the sound environment based on perceptual parameters typically account for the time of presence of sound sources [8], [16]. Finally, factors non-related to the sound, such as visual parameters [17] or others external factors [17]- [20], can also affect the perceived soundscape quality.…”

“…These approaches are encouraged by novel acoustic mapping techniques based on low-cost sensor networks, or participative measurements, which allow obtaining sound maps with a higher spatial resolution, while being sensitive to all kind of sound sources constituting the sound environment [23]- [26]. Studies linking perceptual tests to acoustical measurements showed for instance that better estimates of the pleasantness of sound environments are obtained if parameters describing the temporal variations of sound, the sound spectrum, or the contributions of specific sound sources, are introduced in the modeling [8], [10], [27], [28]. In addition, physical indicators such as L50, Leq or Zwicker's Loudness are most of the time well correlated to the pleasantness or the perceived loudness [8], [11], [29], [30].…”

“…These perceptual parameters can focus on the sound sources that compose the urban soundscape, such as traffic, humans or natural elements, and may describe their time of presence, sound level, or dominance [8], [10]- [12]. Studies report a consensus about the positive contribution of natural sounds and the negative contribution of traffic sounds to soundscape quality, whereas the contribution of human sounds can be either positive or negative.…”

“…It is acknowledged that the quality of sound environments can be characterized by perceptual parameters [8], [10], [11]. These perceptual parameters can focus on the sound sources that compose the urban soundscape, such as traffic, humans or natural elements, and may describe their time of presence, sound level, or dominance [8], [10]- [12].…”

“…Accordingly, alternative approaches are under development, which rely on novel indicators for sound mapping. These approaches are closer to the city dweller's perception, and as such are better descriptors of soundscape quality [2], [6]- [8]. A key point when assessing the quality of urban sound environments is therefore the selection of relevant descriptors that are correlated to perceptual dimensions, which should be easy to understand and handle [9].…”