Speaker
Description
Measuring audible signals in train driver’s cabs currently lacks a normative measurement procedure. New rolling stock must comply with the TSI LOC&PAS which requires the signal level to exceed the background noise level in the cab by 6 dB at maximum speed. Compliance can be demonstrated by direct measurement of the sound pressure level of each sound in the driver’s cab in accordance with EN ISO 3381. The procedure is repeated until a satisfactory signal level is reached. A statement as to whether this procedure is the most appropriate to assess audibility is beyond the scope of the contribution. The purpose is to introduce a new semi-virtual approach that can be summarized as follows•Measurement of source-receiver impulse responses (IRs) in a driver’s cab;•Time-convolution of the measured IRs with the audible signals time series. The input signals for the procedure are any acoustic signals to be reproduced in the driver’s cab. The outcomes are the calculated signals at the receivers’ positions which can be played back and/or level adjusted in post-processing rather than on-the-fly. Initial findings confirm that the semi-virtual approach, within the scope of audibility assessment, yields consistent results with direct measurement. Practical guidance on concerns such as impulse response measurement, level adjustment and system requirements is provided. To conclude, this work aims to provide an innovative alternative to repeated measurements of many warning signals, in turn facilitating a streamlined audibility assessment.This presentation is based on preliminary work carried out by the CEN/TC 256/SC 4/WG 3 “Acoustics” working group, which is responsible for drafting a European standard for evaluating audibility of warning signals in the driver’s cab.