## 1pSA8. Acoustic analysis of plane-wave transmission through a duct of a thick wall.

### Session: Monday Afternoon, December 2

### Time: 4:05

**Author: Ryoichi Sato**

**Location: Dept. of EEE, Chuo Univ., 1-13-27 Kasuga, Bunkyo-ku, Tokyo, 112 Japan**

**Author: Hiroshi Shirai**

**Location: Dept. of EEE, Chuo Univ., 1-13-27 Kasuga, Bunkyo-ku, Tokyo, 112 Japan**

**Abstract:**

Analysis of sound transmission and penetration through a duct of a wall is
one of the basic but important problems in structural acoustics. If the wall is
thin, then the configuration may be regarded as a slit of zero thickness, and
the treatment is rather easy. For the thick wall, however, one has to consider
the duct propagation and the problem becomes somewhat involved. In this paper,
plane-wave transmission through a two-dimensional duct of a rigid wall is
treated rigorously and formulated as a boundary-value problem [K. Hongo and G.
Ishii, IEEE Trans. Antennas Propag. AP-26, 494--499 (1978)]. First, the
scattering field in each region is expressed in terms of appropriate
eigenfunctions with unknown excitation coefficients. Then the continuity
condition of the field at the aperture of the duct has been used for determining
them. Starting from a rigorous solution, one can also derive a simple formula
for estimating the transmission field through a small-aperture duct. Numerical
computations have been done extensively and compared with those by other
methods. Good agreements are found between this solution and others. Validity of
the small-aperture approximation will also be discussed.

ASA 132nd meeting - Hawaii, December 1996