Users of hearing protectors at workplaces may need to be able to hear signals from the work environment. The essential aspects for selection of a hearing protector suitable for this purpose are the audibility of warning signals and sounds containing information in the work environment, and the comprehension of speech at the workplace. The IFA list of approved products (list of all hearing protectors with EC type examination certificate reported to the IFA) assists in selection by stating supplementary codes indicating the signal audibility. The codes are determined by the IFA from the mean values for the sound attenuation measured during the type examination of the hearing protectors.
The significance of the codes is as follows:
The codes W and X take account only of the sound attenuation values of the hearing protectors. Hearing protectors marked in this way are therefore suitable for the majority of workplaces. The three other codes, i.e. S, V and Ex (x = 1 to 3), also include the spectra of signals and background noises at the specific workplaces stated. In Germany, the responsible authorities impose particular requirements upon the signal audibility when hearing protectors are worn in these three areas of work. These requirements are met when a suitably marked hearing protector is selected and its suitability for use at the workplace can be demonstrated by means of a personal hearing test. Procedures for the hearing test can be found in the publications of the accident insurance institutions concerning the relevant areas of work.
The IFA has issued a series of publications on the special requirements in Germany concerning signal audibility when using hearing protectors. They have been gathered in a list (PDF, 180 kB) containing links to the abstracts and in some cases to the full texts.
A list of hearing protectors that are suitable for use in railway operation (engine drivers and engine driver/shunters) can be downloaded here.
A web application can be used to obtain a prognosis of the perceptibility of warning signals for a hearing protector (codes W, X, S, V and Ex in the IFA's list of approved products). The prognosis is based upon sound attenuation values from the type examination of the hearing protector.