W: Criteria “warning signal hearing in general”, “information-containing sounds” and “speech intelligibility” fulfilled (average slope of the mean values of the octave sound attenuation maximum 3.6 dB/octave)
X: Extremely flat insulating hearing protection. May be suitable for persons with hearing loss. May also be suitable for musicians (average slope of mean values of octave sound attenuation maximum 2 dB/octave).
S: Signal hearing possible at the track superstructure.
V: Signal hearing possible when driving and vehicles in public road traffic.
E: Signal hearing possible for train drivers and locomotive shunting drivers in railway operations. Use only permitted after successfully passing the hearing test in accordance with the technical information of the VBG and UVB “Noise protection measures for locomotive drivers and locomotive shunters” (previously BGI/GUV-I 5147).
E1 = Very suitable, especially suitable for people with hearing loss.
E2 = Well suited.
E3 = Limited suitability.
Source: IFA Institut für Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung