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Analysis of warning sounds used in public transportation systems
Author(s)
Date Issued
January 1, 2017
Type
Conference Paper
Abstract
For the safety of passengers, warning sounds are used in public transportation services, for example, when the train doors are closed. Although the audibility of these sounds is normally required and must be regulated by transportation authorities, the associated noise levels are often unnecessarily high, which frequently lead to the passengers’ discomfort and complaints. In this study, we investigated the door-closing sounds used in the Bangkok Mass Transit System (BTS) Skytrain by evaluating the noise levels and spectral characteristics. The maximum A-weighted sound pressure level (LAFmax) was repeatedly measured at 7 representative positions within each car for two types of train, which differed in terms of the location of loudspeakers. The range of LAFmax was found to be 67.4 dBA to 97.2 dBA with the median at 77.1 dBA, and the train type was found to significantly influence the noise level (p=0.006), and so was the location in train car (p<0.001). The spectral analysis revealed that the door-closing warning sounds consisted of strong ~3-kHz tone bursts (with a few harmonics), which were found to be 15~20 dBA above the ambient level. The outcome of the study suggests that the warning sounds used in the BTS Skytrain are likely to distress the passengers due to the excessive playback level and the tonality. Further discussions are made on methods to reduce the psychological impact of the warning sounds on passengers while maintaining a good audibility.
Citation
Inter Noise 2017 46th International Congress and Exposition on Noise Control Engineering Taming Noise and Moving Quiet, 2017-January, 2017