Corrections In Sound Power Level Determination Using Intensity Measurements

[1829] Many Brazilian cities have been facing noise pollution problems. Traffic noise is considered the first annoyance source, followed by civil construction equipments noise. It is paramount to control emission and propagation noise in civil engineering sites to maintain quality of life. Sound power level is an important parameter to predict sound propagation in the environment. The use of intensity measurements makes possible to obtain the sound power level of noise sources in situ, even if other sources are present. With this technique it is not necessary to move the source to reverberation or anechoic chambers. This work studied the efficiency of corrections applied to sound power level determination using intensity measurements. Intensity measurements of electric drills were carried out using a Bruel & Kjaer sound intensity probe. Sound power level was calculated applying corrections suggested in the literature. The results were compared with sound power level measured in special rooms. There was no statistic significant difference between sound power level obtained in special rooms and intensity measurements. With this work the authors intend to spread the intensity measurement technique and use sound power level determination of civil construction equipments to build a support database for environmental noise prediction software.434113420Rott, J.A., (1995) Mapa Simplificado de Ruídos para A Cidade A Cidade de Porto Alegre, p. 145. , Dissertação (Mestrado), Faculdade de Engenharia Civil, Universidade Federal do Rio Grande do Sul, Porto AlegreSchimitt, I.N., Pumo, M.L., Muhle, L.A., Coelho, D., Moura, V.P., Oliveira, R.S., Gestão ambiental no controle da poluição sonora: A experiência de Porto Alegre Proceedings XIX Encontro Da Sociedade Brasileira de Acustica, 2000, Belo Horizonte, pp. 398-415Rolla, S., Ruído na construção civil Proceedings XVII Encontro Da Sociedade Brasileira de Acústica, Petrópolis,, Florianópolis, 1996, pp. 352-359Maia, P.A., (2001) O Ruído Nas Obras Da Construção Civil, e O Risco de Surdez Ocupacional, p. 145. , Dissertação (Mestrado), Faculdade de Engenharia Civil, Universidade Estadual de Campinas, CampinasJacobsen, F., State of art of sound intensity and its measurements and applications Proceedings 17th International Congress of Acoustics, Roma, 2001, 2Santos, C., (2004) Investigação Sobre Métodos de Determinaç ão Da Potência Sonora Visando O Programa de Etiquetagem de Ferramentas Elétricas de Uso Doméstico, , Dissertação (Mestrado), 128pp, Faculdade de Engenharia Civil e Arquitetura, Universidade Estadual de Campinas, CampinasFahy, F., Measurement of acoustic intensity using the cross spectral density of two microphones signal (1977) Journal of Acoustical Society of America, 62, pp. 1057-1059Chung, J.Y., (1977) Cross-spectral Method of Measuring Acoustic Intensity, , Research Publication of General Motors, Michigan(1995) Acoustics Determination of Sound Power Levels of Noise Sources Using Sound Intensity - Measurements for Scanning, , International Organization for Standardization, ISO 9614-2, Geneva(1999) Acoustics Determination of Sound Power Level of Noise Sources Using Sound Pressure, Precision Methods for Reverberations Rooms, , ISO 3741, Geneva(1994) Acoustics Determination of Sound Power Level of Noise Sources Using Sound Pressure, Comparison Method for Hard Walled Test Rooms, , ISO 3743-1 Geneva(1994) Acoustics Determination of Sound Power Level of Noise Sources Using Sound Pressure, Method for Special Reverberation Test Rooms, , ISO 3743-2 GenevaJacobsen, F., Spatial sampling errors in sound power estimation based upon intensity (1991) Journal of Sound and Vibration, 145 (1), pp. 129-149Jacobsen, F., Cutanda, V., Jhul, P.M., A sound intensity probe for measuring from 50 Hz to 10 KHz (1996) Proceedings Internoise 96, Liverpool, pp. 3356-3361Hübner, G., Wittstock, V., Investigations into correlation between field indicators and sound absorption Proceedings 17th International Congress of Acoustics, Roma, 2001, 2Hübner, G., Wittstock, V., Wittstock, V., Further investigations to check the adequacy of sound field indicators to be used for sound intensity technique determining the sound power level Proceedings Internoise 99, Fort Lauderdale, 1999, pp. 1523-152