Impact-noise reduction by floor coverings
S. Nakamura, Masaru Koyasu · The Journal of the Acoustical Society of America · 1978
Measurements were made under various impact conditions as follows: Hammers of mass = 200 g, radius = 50 cm; mass = 500 g, radius = 50 cm; and mass = 500 g, radius = 2.5 cm; and fall height of ∼32 cm. First the usual frequency characteristics of ΔL were obtained by a 13-octave-band frequency analysis for a single impact sound with a multichannel analyzer operating in fast and Max-hold modes. Since the shape of the ΔL curves are, as is well-known, very simple and resemble each other, it is enough to take f0, the frequency where the curve rises up from the horizontal axis. In addition, our results show a noticeable close relationship between f0 and such level difference as L(dBC) − L(dBA), measured with a test covering. Finally, it was found reasonable to illustrate the experimental results on a diagram of MHR−1/2 vs f0H−1/2; that is, the properties of a sample are shown as a single curve indicating clearly the individual characteristics. For instance, the slope of the curve for carpet has a sudden change at a certain impact condition, and so-called needle-punch carpet is quite different from a usual elastic plate.