661 research outputs found
The acoustic characterization of green materials
No full textNatural materials are a valid alternative to traditional synthetic materials in the fields of acoustic treatments and energy saving. Natural fibres have been used to produce sound-absorbing panels. This article reports the acoustical characterization of the following natural fibres: straw, hay, plant litter and different sized wood chips. The acoustic measurements were carried out with an impedance tube. The acoustic absorption values were measured in a frequency range between 200 and 2000 Hz
Effects of noise from wind turbines inside home
No full textThe inland areas of southern Italy were built with many wind farms which are often situated close to houses. This work reports the results of acoustic measurements made in a room inside a house located near a wind farm. The acoustic measurements were carried out during the autumn season; the values of LeqA and L95 have been measured for different wind speeds
Ceramic material for sound absorption
No full textThe acoustic correction of large places for low frequency components can be obtained by inserting acoustic resonators. This paper reports the realization and the experimental verification of acoustic resonators obtained with ceramic material. The sound absorption is obtained by drilling the specimens of ceramic material with a hole size of 2 mm and 5 mm and a thickness of 3.0 cm, 2.0 cm and 0.6 cm. The sound absorption of perforated plates is based on the principle of Helmholtz resonators, which, however, are effective only on narrow frequency bands; so to make the phenomenon of absorption more effective and to increase the range in absorption frequency perforated panels are made, mounted at a suitable distance from a rigid surface. The measurements of the sound absorption coefficient were performed with an impedance tube (Kundt tube) with an internal diameter of 10 cm and with the validity of the measurement of the absorption coefficient in the range of 100 Hz - 1.0 kHz. The measurements of the absorption coefficient were performed, for each specimen, creating a cavity of air between the sample and the behind rigid surface, with the following thicknesses: 25 cm, 20 cm, 15 cm, 10 cm and 5 cm. As expected, for the same specimen, the peak of the absorption coefficient shifts to higher frequencies on decreasing size of the cavity between the specimen and the rigid wall
SUPPORTO UNIVERSALE PER LA FOTOGRAFIA PANORAMICA A 360°
No full textSUPPORTO UNIVERSALE PER LA FOTOGRAFIA PANORAMICA A 360°, IN USO PER TABLET E TELEFONI CELLULAR
Wind turbines noise measurements inside homes
No full textThe rapid expansion of energy produced by wind power has increased the interest in the possible harmful effects on the health of the residents in the areas near to wind farms. It is therefore important to understand how to reduce these effects. This article analyses the results of noise measurements carried out in homes located near a wind farm in Southern Italy. Two sound level metres for the contemporary acquisitions of noise levels were used, placed in two different homes: three wind towers were visible from one measurement point, while only one wind tower could be seen from the other point. The acoustic measurements were performed under different weather conditions as well as with different wind speeds and directions. The same conditions were measured when the system was on and off. The measured sound levels were then compared so as to establish the wind velocity ranges where the part of noise generated by the rotating of the blades (ambient noise) prevails as well as the wind velocity ranges where the wind noise (background noise) prevails. The analysis of the data shows how for low wind speeds, the noise generated by the rotating of the blades is considered an annoyance by the people who live near the farm. While for greater wind speeds, the noise generated by the rotation of the blades is covered by the noise of the wind, with it therefore not being perceived
Acoustic correction of monumental churches with ceramic material: The case of the Cathedral of Benevento (Italy)
No full textIn this work, soundproof systems for the acoustic correction of large spaces, such as monumental churches, are studied. The Cathedral of Benevento is considered as a case study. Dated back to the seventh century, the church was destroyed during the Second World War and rebuilt in the mid-twentieth century, using marble for the floor and smooth plaster for the side walls. In the current state, the cathedral exhibits an excessive reverberation time (about 10 s) that causes poor understanding of speech and not good listening to musical performances. It is difficult to perform any form of acoustic correction inside the cathedral, since the walls and the ceiling cannot be covered with traditional sound-absorbing material due to architectural and aesthetic reasons. Therefore, the possibility of using ceramic material applied to the side walls for the acoustic correction of low-frequency components and transparent micro-perforated sheets placed under the ceiling for the acoustic correction of medium- and high-frequency components are considered. The work is divided into three phases: in the first phase, measurement of the current acoustic characteristics of the cathedral is performed. In the second phase, sound absorption material is investigated and in the third phase, the effects of insertion of soundproof systems on the acoustic characteristics of the cathedral are theoretically evaluated by means of a room acoustic software
L’acustica dei Teatri in Campania, dall’antichità al 1700: dal Teatro Romano di Benevento al Teatro di Corte della Reggia di Caserta
No full textThe use of historical courtyards for musical performances
No full textThis work reports the measurements of the acoustic characteristics carried out in three historic courtyards set up for musical performances. Even if the courtyards are not necessarily suitable locations for musical events, due to organizational reasons, with it being possible to control the audience, along with the suggestiveness of the places, they are chosen by the organizers and are highly popular and appreciated by both musicians and singers alike. The acoustical problems are due to the absence of the ceiling, which does not re-send the sound into the room, as well as the flat and parallel walls that generate unwanted multiple reflections. The acoustic study of the courtyards was carried out according to the standard ISO 3382 by placing a sound source on the stage where the musicians sit and the microphone receivers in the courtyard in the absence of the audience. Furthermore, the spatial distribution of the acoustic parameters in the presence of the audience was evaluated using architectural acoustics software
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