Tom De Muer

A model for the perception of environmental sound based on notice-events

An approach is proposed to shed light on the mechanisms underlying human perception of environmental sound that intrudes in everyday living. Most research on exposure-effect relationships aims at relating overall effects to overall exposure indicators in an epidemiological fashion, without including available knowledge on the possible underlying mechanisms. Here, it is proposed to start from available knowledge on audition and perception to construct a computational framework for the effect of environmental sound on individuals. Obviously, at the individual level additional mechanisms (inter-sensory, attentional, cognitive, emotional) play a role in the perception of environmental sound. As a first step, current knowledge is made explicit by building a model mimicking some aspects of human auditory perception. This model is grounded in the hypothesis that long-term perception of environmental sound is determined primarily by short notice-events. The applicability of the notice-event model is illustrated by simulating a synthetic population exposed to typical Flemish environmental noise. From these simulation results, it is demonstrated that the notice-event model is able to mimic the differences between the annoyance caused by road traffic noise exposure and railway traffic noise exposure that are also observed empirically in other studies and thus could provide an explanation for these differences.

Uncertainty in noise mapping: comparing a probabilistic and a fuzzy set approach

Complex georeferenced simulation resulting in immission maps loose credibility because of lacking or poor quality input data and model approximations. For modeling the resulting imperfection in the maps, several techniques can be used. In this paper we briefly compare a probabilistic approach implemented using Monte Carlo and a Fuzzy Approach. The theoretical foundations are highlighted and their consequences for the simulations are outlined. An experiment is set up to compare practical results of both techniques. Despite numerical differences in results, both techniques prove usable while the Fuzzy Approach has a clear advantage in calculation speed compared to a Monte Carlo Approach.

Noise annoyance mapping

Geographical Information Systems (GIS) allow attaching different types of information to geographical primitives. Compared to general-purpose databases, these spatial databases are augmented with a number of functions directly related to geography. Queries based on distance, surface, and spatial aggregation are but a few examples. Even more important are the extended possibilities for visualization that a typical GIS application offers. Because of these, GIS are now becoming very popular in applications related to different fields and in particular play an important role in policy decision support. The policy maker has all available information at his or her fingertips and can identify “black point” or areas of potential interest at a glimpse. This chapter focuses on applications where human perception plays an important role and on EIA(Environmental Impact Assessment). It is build around a particular case: the assessment of noise annoyance, but concepts and methods introduced are obviously much broader. There are two great points of concern when addressing the aforementioned application areas using classical GIS. Firstly, working with human perception of for example the quality of life, the quality of the living environment, safety, or disturbance by noise or odor, quickly introduces a kind of vagueness, that classical GIS cannot easily store nor process.

1/f dynamics in the urban soundscape

Urban soundscapes are characterized by much more than loudness alone. Subjective description has been used by many researchers to grasp these additional dimensions, but very little objective criteria are found in literature. In this paper the dynamics of the soundscape is proposed as a potential indicator. By analyzing loudness and pitch fluctuations in longer sound fragments recorded in urban environment, 1/f spectral behavior at frequencies ranging from 0.01 to 10 Hz was discovered. Such behavior is typical for complex systems and was found to be very common in (classical) music, already in the seventies. Some hypotheses will be given on the origin of this frequency dependence of urban‐soundscape dynamics. The possibility of discriminating soundscapes on the basis of the frequency dependence of loudness and pitch fluctuation will be illustrated. For this purpose the urban soundscapes are compared to ‘‘extreme’’ soundscapes that have a very distinct character that is clear to every observer.

Microscopic traffic modelling in urban noise assessment

The temporal structure of the urban soundscape can be rather complex, due to the presence of many screening and reflecting surfaces and many different sound sources, of which traffic noise is the most dominant. From the point of view of soundscape research, the background level as well as the time structure of noise peaks are important. However, these indicators cannot be estimated easily by current noise prediction models, based on static traffic flows. Therefore, a dynamic traffic noise model was used, based on a microscopic traffic simulation. This way, individual vehicles can be traced, each having an associated set of noise sources that can depend on vehicle properties such as speed and acceleration, as well as on road properties such as the surface type. The model further consists of an ISO 9613 based propagation component, which can account for multiple reflections and diffractions. Maps of statistical noise levels, but also of more complicated measures reflecting the time structure of the soundsca...

An LAeq is not an LAeq.

Classical dose response relationships for environmental noise annoyance have been based on Ldn or Lden. These exposure measures are essentially based on an energy averaging measure, LAeq. Differenc ...