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The Acoustic Characterization of Broom Fibers
No full textNatural materials are becoming a valid alternative to traditional synthetic ones for sound absorption applications. In this paper, the acoustic properties of broom fibers are reported and discussed. Broom plants grow up on hills and mountains and are common in many Mediterranean countries. The materials were cut and shredded to prepare several samples. Test specimens made of broom pieces with a diameter from 1.5 mm to 4 mm were prepared. The normal sound absorption for samples with a thickness of 60 mm, 80 mm and 120 mm was then measured. Results are particularly promising especially above 500 Hz, as the samples consistently reported a normal sound absorption above 0.5. The increase in the sample thickness allowed to obtain higher sound absorption at lower frequencies, as generally expected for porous materials. The main limit of the investigated samples was the appearance of sound absorption resonances. These were more evident for the samples composed of pieces with larger diameter, and may be attributed to the loose nature of the tested samples
Characterization of sheep wool panels for room acoustic applications
No full textGiven the good thermal and sound absorption properties, the lack of harmful effects on health, and the availability in large quantities, natural fibers are becoming a valid option for sound absorption panels in building applications. This paper investigates sheep wool fibers and panels. The absorption coefficient and the static flow resistivity for samples of different thickness are measured and discussed. Then, the possibility of using fabrics obtained with different kinds of woven wool as sound absorbing systems is investigated. For this scope, wool tapestries were mounted at a variable distance from the rigid back wall. The high absorption obtained in some frequency bands, depending on the back cavity depth, confirmed the possibility of using wool tapestries for ad-hoc customized acoustic interventions. Finally, this paper discusses the advantages of adopting sheep wool for room acoustic applications
Urban soundscape appraisal in laboratory: a tool for testing and improving urban renewal
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A preliminary investigation on some psychological and acoustic aspects of wind farms' noise annoyance
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Merging physical parameters and laboratory subjective ratings for the soundscape assessment of urban squares
No full textAn experimental study was carried out in 20 squares in the center of Rome, covering a wide range of different uses, sonic environments, geometry, and architectural styles. Soundwalks along the perimeter of each square were performed during daylight and weekdays taking binaural and video recordings, as well as spot measurements of illuminance. The cluster analysis performed on the physical parameters, not only acoustic, provided two clusters that are in satisfactory agreement with the “a priori” classification. Applying the principal component analysis (PCA) to five physical parameters, two main components were obtained which might be associated to two environmental features, namely, “chaotic/calm” and “open/enclosed.” On the basis of these two features, six squares were selected for the laboratory audio-video tests where 32 subjects took part filling in a questionnaire. The PCA performed on the subjective ratings on the sonic environment showed two main components which might be associated to two emotional meanings, namely, “calmness” and “vibrancy.” The linear regression modeling between five objective parameters and the mean value of subjective ratings on chaotic/calm and enclosed/open attributes showed a good correlation. Notwithstanding these interesting results being limited to the specific data set, it is worth pointing out that the complexity of the soundscape quality assessment can be more comprehensively examined merging the field measurements of physical parameters with the subjective ratings provided by field and/or laboratory tests
Sviluppo di metodologie innovative a supporto degli studi di impatto acustico nelle valutazioni di impatto ambientale
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