Curve fitting procedures for high speed trais measured noise levels
Type de document
Résumé / Abstract
The noise of high speed trains is known to result from two main types of sources: a rolling noise which predominates at low speeds and an aerodynamic noise which predominates at high speeds. It is usually characterized by sound pressure levels, measured at a given distance (25 m for instance) as function of the train speed (passby noise levels). The knowledge of the contribution of each component to the total noise is important : one can wish for instance to evaluate the reduction of the total noise which could result from a reduction of the rolling noise, or to evaluate what will be the noise at speeds higher than the measured range (extrapolation of the known levels). On the other hand, one can merely wish to synthesize the measured results through a single curve given by a simple analytical expression. In this report we evaluate, using simulated examples, the performances of various techniques which can be used to evaluate the rolling and aerodynamic contributions from measured passby noise levels or to synthesize these levels.