Emergency warning signal (EWS) sounds have been developed to improve safety for railroad workers and warn trespassers. Researchers conducted a literature review that addresses the need for a new EWS sound, the types of warning sounds used in railroad and non-railroad settings, and fundamental principles of human hearing as it relates to signal detection and masking effects from headphones and music. Preliminary EWS sounds were developed and their effectiveness evaluated with a listening survey. The survey measured the detectability, sense of urgency, identification/association of the sound with a train and the startle effect of various EWS sounds. Candidate EWS sounds were optimized and tested in an audio booth where participants listened to music with headphones while warning signals were reproduced to simulate a train approaching. Two candidate EWSs and a typical train horn sound were tested on board a moving locomotive on TTC tracks. The EWS sounds were reproduced using an acoustical warning device speaker system and the response times of participants wearing hearing protection or headphones were measured. This research shows that an EWS could maintain its association/identification of a train approaching, improve detectability, and provide more time to persons wearing headphones to vacate the tracks.

See Also:

• Acoustical Warning Devices as Emergency Warning Systems, Phase 1
• Acoustical Warning Devices as Emergency Warning Signals, Phase 2