## 4aPA4. Propagation of finite-amplitude broadband noise.

### Session: Thursday Morning, May 16

### Time: 8:45

**Author: Penelope Menounou**

**Author: David T. Blackstock**

**Location: Appl. Res. Labs., Univ. of Texas, Austin, TX 78713-8029 and Mech. Eng. Dept., Univ. of Texas, Austin, TX 78712-1063**

**Abstract:**

Burgers' equation is used to predict the effect of nonlinearity on the
power spectral density of plane broadband noise traveling in a nondispersive
thermoviscous fluid. The source signal is assumed to be stationary Gaussian
noise, which, because of nonlinear propagation distortion, becomes non-Gaussian
as it travels. As opposed to time-domain methods, the method presented here is
based directly on the power spectral density of the signal, not the signal
itself. The Burgers equation is transformed into an unclosed set of linear
equations that describe the evolution of the joint moments of the signal. A
method for solving the system of equations is presented. Only the evolution of
appropriately selected joint moments needs to be calculated in order to predict
the evolution of the power spectral density of the signal. The results are in
good agreement with a time-domain code [Cleveland et al., J. Acoust. Soc. Am.
98, 2865(A) (1995)]. The method can be also applied when the source condition is
a stationary, ergodic, and Gaussian stochastic process. [Work supported by
NASA.]

from ASA 131st Meeting, Indianapolis, May 1996