Study of vertical noise profile through Helium-filled-balloon measurements in the city of Milan, Italy

Considering the actual "vertical" housing development in the last few decades, the number of people living in high-rise building is increasing. At present in the city of Milan about 500 (0.4% of total) buildings exceed the height of 50 m, with a number of residents of about 14000 (1% of total). For this reason, we planned an experimental campaign to study the vertical noise profile through Helium-filled-balloon measurements in the city of Milan, Italy. Results show that the noise levels increase with the height with respect to a ground-reference measurement, as a result of the contribution coming from an extended area. The highest levels are reached at about 90 m. Critical issues regarding this measurement technique are also outlined.