Part III: Measuring hearing-critical job tasks 129 This research revealed that the noise levels in Dutch train cabins range between 53.2 and 77.1 dBA, depending on the train type and driving speed. Although the levels of the auditory warning signals are higher than the background noise levels, the acoustical requirements for signal detectability were not met in multiple driving conditions, especially at higher speed. Normally-hearing subjects who can make use of high frequency signal peaks were able to compensate for the suboptimal acoustic conditions, but difficulties can be expected in unfavourable driving situations or when the engineer suffers from hearing loss. To ensure safe and effective job performance in all driving situations, the detectability of warning signals in Dutch train cabins warrants further attention, particularly when hearing loss is present. Acoustical, environmental or work modifications might be required to prevent situations with insufficient audibility in hearing-impaired engineers.
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