Mauro Cerchiai

Low frequency noise impact from road traffic according to different noise prediction methods

The European Noise Directive 2002/49/EC requires to draw up noise action plans. Most of the implemented solutions consist in using barriers, even if some studies evidenced that annoyance could increase after their installation. This action dumps the high frequencies, decreasing the masking effect on low ones. Therefore, people annoyance and complaints may increase despite the mitigation. This can happen even in pedestrian zones near main roads due to the screening effect of first buildings row. In this paper, the authors analyze the post-operam screening effects in terms of low frequency noise. The difference between C- and A-weighted levels is calculated as annoyance indicator (LC-A). Different methods able to map noise with octave bands detail are tested in order to establish differences in the estimates of annoyance exposure. In particular, a comparison is carried out between data from interim method NMPB 96, its updated version 2008, NORD 2000 and those provided by a customized procedure through ISO 9613 propagation and Statistical Pass By measurements. Test sites are simulated in order to validate each model results through measurements. Results are discussed for real locations in Pisa city center and virtual scenarios in a rising scale of complexity.

Perspectives for a strategical mapping of soundscapes

The transposition of the European Noise Directive by Member States gives a new way to action plans of urban areas, underlying (article 6 and Annex III) that dose‐effect relations should be used to assess the effect of noise on populations. Particular interest, in this sense, has the relationship between annoyance and perceived soundscape: it is now almost accepted that a higher annoyance is not always proportional to higher noise levels. This paper will demonstrate that a way to move from mapping noise exposure to a map of annoyance passes through the characterization of the soundscapes present on the territory. A numerical indicator (“slope”), derived from the time history of the measured sound/noise, will in fact be used to characterize the evolution along the day of the soundscapes present in the city of Pisa (I). In particular, “slope” (correlated to annoyance in previous studies) will be used to prepare a map of the annoyance in selected areas of Pisa: predicted annoyance will be to be compared with ...

Road noise characterization by Harmonoise procedures reviewed for the Italian case

Several methods have been introduced to describe acoustical properties of road pavements in situ, such as the extended surface technique (Adrienne), the Statistical Pass‐By and the Close Proximity methods. In general the aim of these techniques, normed in ISO standards, is to evaluate some indexes that may be representative of noise generation and propagation with respect to tyre‐road interaction and surface absorption. In this paper we use results obtained in the LEOPOLDO project, that involves measurements carried out on many sites all over Tuscany Region characterized by typical conditions of Italian roads, to review the state‐of‐the‐art of acoustical parameters in the modelling of road vehicles showed in the HARMONOISE documents. This task has been accomplished by comparing the theoretical results obtained from the HARMONOISE prediction method with the energy levels measured at the microphone locations close to the road borders, in order to apply corrections to the parameters influencing sound generat...

Mapping soundscapes in urban quiet areas

Innovative action plans in noise‐polluted environments require the description of the existing soundscape in terms of suitable indicators. The role of these indicators, giving the ‘‘fingerprint’’ of a fixed soundscape, would be not only to measure the improvement in the sound quality after the action taken, but also to guide the designer in the process, providing a reference benchmark. One of the open questions on new indicators is the way they relate to existing ones and to people’s perception. The present work will describe a ‘‘Sonic Garden’’ in Florence, using both the ‘‘slope’’ indicator (constructed from the LAeq time history and related in previous studies to people’s perception) and classical psychoacoustical parameters (level, spectral structure, and perceived characteristics such as loudness, sharpness, fluctuation, and roughness). The latter parameters will be acquired using a binaural technique.

Simnoise: A new low‐traffic‐flow road noise estimation by a statistical approach

Road noise models usually limit the possibility of sound‐level prediction with low vehicular fluxes, especially during the night period, because they provide urban traffic noise with a minimum number of some hundreds of vehicles per hour. In order to predict sound levels in urban areas for both night and day periods and to plan corrective actions, a model that can be applied in case of very low traffic flows (even lower than 50 vehicles for hour) is proposed here. This model uses a Monte Carlo method based on a dependent Poissonian vehicle distribution, a spatial Gaussian one with respect to the lane center, and a Cauchy distribution for velocities. These are estimated using the English Road Research Laboratory model, calibrated using only geometrical site description and vehicular fluxes informations, based on 75 measurement points in a speed range between 20 and 60 km/h, for almost 230 hourly night Leq levels. The prevision values resulted in good agreement with actual values with an error depending on ...