## Abstract

The dynamic compressibility of air in fibrous materials has been
computed for two assumed configurations of fibers which are close
to the geometry of real fiber materials. Models with parallel
cylinders placed in a regular square lattice and placed randomly
are treated. For these models the compressibility is computed
approximately from the diameter and mean distances between
cylinders. This requires calculation of the air temperature, which
is calculated for cylinders in a regular lattive by the
Wigner-Seitz cell approximation. In the case of random placement,
the calculation is done by a summation over thermal waves from all
fibers, and by a self-consistent procedure. Figuren of the
compressibility in the frequency range 10-100 000 Hz, are given
for diameter of the cylinders of 6.8 µm, and mean distances
between them from 50 to 110 µm, which corresponds to glass wool
with a density of 40 to 16 kg/m3. When the theoretical values for
random placement were compared with measurements, it turned out
that the random model could not describe the experimental data.
However, they could be described accurately by assuming that the
fibers have a tendency to form pairs.

Original language | English |
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Journal | Acoustical Society of America. Journal |

Volume | 99 |

Issue number | 5 |

Pages (from-to) | 3010-3017 |

ISSN | 0001-4966 |

DOIs | |

Publication status | Published - 1996 |