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  • 1.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Sweden.
    Simmons, Christian
    Luleå University of Technology, Sweden; Simmons Akustik och Utveckling, Sweden.
    Hagberg, Klas G.
    Correlation between sound insulation and occupants' perception – Proposal of alternative single number rating of impact sound2014Inngår i: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 85, s. 57-68Artikkel i tidsskrift (Fagfellevurdert)
  • 2.
    Olsson, Jörgen
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Bygg och fastighet. Linnaeus University, Sweden.
    Linderholt, Andreas
    Linnaeus University, Sweden.
    Measurements of low frequency impact sound frequency response functions and vibrational properties of light weight timber floors utilizing the ISO rubber ball2020Inngår i: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 166, artikkel-id 109343Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Impact sound performance below 100 Hz forms part of a design criterio that is particularly important for multi-story timber buildings. An ISO tapping machine, which is predominantly used for impact sound measurement, has properties that may result in less measurement accuracy in the low frequency range, down to 20 Hz, than in its traditional measurement range above 100 Hz. The characteristics of the pistons’ impact are dissimilar to the impact of a human foot in this lower range. This may cause low signal-to-noise ratios in field measurements and the test data may also be less representative due to the test objects’ possible structural nonlinearities affecting impact sound transmission. The ISO rubber ball has shown to bear a close resemblance to a human’s excitation in the low frequency range, which makes it a suitable excitation device from this perspective. To support correlations between simulations and measurements, measuring impact forces in order to extract frequency response functions would be beneficial. To enable measurements of impact forces that stem from the ISO rubber ball, equipment for field measurements of forces and potentially point mobilities has been manufactured and evaluated. Furthermore, an investigation has been conducted into the repeatability of the rubber ball’s low frequency force spectrum for floors with different mobilities. Impact force measurements have been made on lightweight timber floors as well as on concrete floors. Within the frequency range up to around 55 Hz, it appears to be possible to use a prescribed force spectrum for the ISO ball, together with impact sound measurements, to create accurate impact force to sound frequency response functions for different floors. Also, instrumenting the impact point with an accelerometer enables estimates to be made of direct point mobilities.

  • 3.
    Olsson, Jörgen
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Bygg och fastighet.
    Linderholt, Andreas
    Linnaeus University, Sweden.
    Jarnerö, Kirsi
    RISE Research Institutes of Sweden, Samhällsbyggnad, Bygg och fastighet.
    Hongisto, Valtteri
    Turku University of Applied Science, Finland.
    Incremental use of FFT as a solution for low BT-product reverberation time measurements2023Inngår i: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 203, artikkel-id 109191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The limitations in performance of band-pass filters to accurately process rapid decaying signals in lower frequency bands is an obstacle for some measurements within building acoustics. For instance, it would be beneficial to be able to accurately measure reverberation times down to the 20 Hz one-third octave band for impact sound in timber buildings. Here, it is tested whether calculations with FFT with small incremental steps may be a way to achieve discrete frequency time signals with faster performance than traditional band-pass filters. The tests show that incremental FFT gives accurate estimations of the reverberation time corresponding down to 0.1 s at 20 Hz with a spectral resolution of 2 Hz. Using the one-third octave limits it is possible to form approximate one-third octave band results. It is seen that accurate estimations of reverberation time are achievable for BT⩾0.5 (T=0.1 seconds for the 20 Hz one-third octave band) and possibly even lower, if the dynamic range in the interrupted noise signal is sufficient. The higher one-third octave results show to work as well. A disadvantage with the method is that during short reverberation times (0.1 s) there is a severe spectral leakage to the side bands. Also, the method requires higher dynamic range decay signals compared to band-pass filtered signals. If a one-third octave resolution is requested, a dynamic range of 50 dB or greater is preferable. With a coarse resolution of e.g., 10 Hz and having no averaging into one-third octave bands, it is possible to measure short reverberation times (0.1 s) with signals having close to the same dynamic range used in classical band-pass filtered reverberation time measurements. © 2022 The Author(s)

  • 4.
    Sjökvist, Lars-Göran
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP Trä.
    Brunskog, J
    An experimental and statistical study of the behavior of the vibration field in two coupled lightweight wooden joist floors2013Inngår i: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 74, nr 4, s. 517–520-Artikkel i tidsskrift (Fagfellevurdert)
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