Quantifying the annoyance caused by flat tops on the wheels of railway vehicles

Abstract

As part of a research project by the Federal Environment Agency measurements of the pass-by noise of railway vehicles with and without flat spots on the wheels were conducted. The aim of the project was to define an acoustic maintenance criterion for the wheels. To do so listening tests were carried out to quantify the annoyance the noise caused by a flat spot. In order to determine the level adjustment equivalent to the increased annoyance caused by the flat spot, the following method of adjustment was used. The test subjects were each presented a pair of sounds consisting of a vehicle passing with and a vehicle passing without a flat spot. By raising or lowering the level of the signal without a flat spot, the test subjects were able to adjust the two signals individually to "equal annoyance". Furthermore different noise levels and psychoacoustic indices were tested in order to describe the impact of the flat spot on the caused annoyance.