## 1pNSb1. The propagation of high-speed train noise above an impedance ground.

### Session: Monday Afternoon, December 2

### Time: 4:30

**Author: Kai Ming Li**

**Location: Eng. Mech. Discipline, Faculty of Technol., The Open Univ., Milton Keynes MK7 6AA, United Kingdom**

**Abstract:**

Transportation noise sources are usually in motion. Previous analyses have
simplified the problem by assuming a moving source either as a quasistationary
point source or, in the case of traffic noise as a continuous line source
problem. This assumption is valid for a vehicle traveling at low speed but is
unlikely to be adequate for a source traveling at a non-negligible Mach number.
A notable example is a high-speed train traveling in excess of 200 km h[sup -1].
In this paper, as a first approximation, the high-speed train is modeled as a
moving monopole source above an impedance ground. Although the sound field due
to a moving monopole source in an unbounded medium is well known, there is
relatively little attention focused on a moving point source near to an
impedance ground surface. Asymptotic analysis has been conducted to derive a
closed-form analytic solution. The project described in this paper is a
canonical problem. The solution (Green's function) will be a building block for
modeling noise propagation due to high-speed trains in future studies which
includes, for example, a moving line source and a moving dipole, etc. [Work
supported by EPSRC, UK.]

ASA 132nd meeting - Hawaii, December 1996