In terms of space Reverberation Time, overall background sound can be measured; about users their behavior, usual activities, social and demographic factors are essential factors

The research proposed in these thesis is related to environmental acoustics; it focuses on noise control in urban sites and it takes part in the European HOSANNA project, a collaborative project under the Seventh Framework Programme, Theme 7, Sustainable Surface Transport. It started in November 2009 and is planned to run for three years. The project is coordinated by Chalmers University of Technology. The main aim is reduction of road and rail traffic noise in the outdoor environment. The innovative proposal consists in the use of green surfaces and various types of vegetation on different urban and rural surfaces such as buildings facades and roofs, trees planting innovative barriers made from recycled materials and green walls substrate to abate : noise. My research purposes to verify it vegetation can really affect and reduce traffic noise in typical

European urban configurations. The case study sites will include a square and a courtyard, in where buildings are one dose to each other; so acoustic reflections can provide an important amplification of sound, increasing Reverberation Time, with the consequence of increment the negative perception on top of the increased loudness. Two real case studies that can be considered as typical European configurations have been chosen, namely one in Torino and one in Sheffield. This provide the opportunity to compare results obtained from simulations with results from in-situ measures. First measures in-situ have been carried out and then, for each case, different noise abatement schemes, based on the guidelines of HOSANNA programs, have been proposed. The selected case sites, both in Torino and Sheffield, are on the list of historical consolidate urban spaces, therefore the green treatments should be completely reversible. I had to be confronted whit a problem which is difficult to solve, the presence of historical noteworthy buildings and consequent architectural constraints. In the case of Torino there exists a strong regulation named Piano Regolatore according to which no changes in a look of historical facades can be made. Also Authorities of Sheffield have drawn up documents for historical buildings called Statements of Special Interest which recognize value of certain buildings. Therefore the noise abatement schemes had to take into account a dual problem, namely they should help in noise reduction from one side and preserve thè architectural value from the other side. The purpose of this thesis was to propose noise abatement configurations which will pay a respect to the historical value of architecture and that could be evaluated by public administration with a view to sustainable urban development, in which outdoor quality is taken in consideration. For each case study, acoustic simulations for reference configurations (without vegetation) had been performed using the software CATT-Acoustic;, then simulations have been repeated with two other software, namely CRR (Combined Ray-tracing and Radiosity) and Odeon, for one configuration. The purpose of these round robin simulations was to verify the results of simulations and to study the applicability of the software for dealing with outdoor sound field propagation. Different geometrical models, different spaces sizes, types and amounts of vegetation have been evaluated, founding out that better results, in terms of traffic noise reduction, can be achieved by using green wall instead of climbing wall and that depending on size of a certain urban space amount or placement of vegetation can play an important role.