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Fakulteta za strojništvo, Ljubljana (FSLJ)
  • Measurement of sound absorption in a very near field [Elektronski vir]
    Prezelj, Jurij ...
    During the reconstruction process of the concert hall acoustic it is important to have some information about the sound absorption coefficient of already installed and applied materials. A new ... in-situ method for measuring the sound absorption was developed. Presented method utiliyes a dipole characteristic of the source, which generates the test signals. A dipole source in a perfect free field conditions generates a specific shape of the sound field. If the dipole source is placed in the vicinity of arbitrary acoustic obstacle, sound field is deformed and it depends only on the acoustic properties of the obstacle. A difference between the sound pressure field of the dipole source in a perfectly free field conditions and the sound pressure field just above the acoustic obstacle gives sufficient information for the calculation of the sound absorption of the obstacle itself. A Rayleigh integral was used for numerical calculations of the sound pressure in a Very Near Field. Results indicate that the size of the dipole source should be as small as possible, but it should provide sufficiently high sound pressure levels. Numerical results indicated that it should be placed as close as possible to the surface of the sample to achieve good signal to noise ratio. Based on the numerical results, a measuring setup was build. A 8 cm dipole source was used and it was placed 2 cm above the acoustic obstacle. Measurement results were compared with results obtained with the Impedance tube.
    Vir: Euronoise 2012 [Elektronski vir] : [proceedings] (Str. 1136-1141)
    Vrsta gradiva - prispevek na konferenci ; neleposlovje za odrasle
    Leto - 2012
    Jezik - angleški
    COBISS.SI-ID - 12349467

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