**1. Introduction**

Historically, the earliest descriptions about the danger of noise-induced hearing loss (NIHL) were described in 1713 by the Italian physician Bernardino Ramazzini (1633–1714). In his book "De Morbis Artificum" (Diseases of Workers), he firstly demonstrated the impact of hearing loss together in a relation to prolonged exposure to noise by his observations based on his examinations on coppersmith workers who were constantly exposed to noise and gradually suffered from hearing loss [1].

During the eighteenth century with onset of rapid industrialisation, the incidence of NIHL increased drastically and lead to the first ideas of preventive actions.

Almost 200 years later, the Hungarian biophysicist Georg von Békésy (1899–1972) analysed the travelling wave of sound in the cochlea, for which he received a Nobel Prize in 1961 and simultaneously set the cornerstone for the start of investigations of noise and hearing loss in relation to exposure time [2].

The origin of the noun "noise" is found in Latin language from the term "nausea", which later via detours through French language was introduced as "noise" to the English language [3]. Both words have much more in common than suspected before.

Substantially, there is no difference between sound and noise. But enlightening the differences more closely, sound refers to the sense of perception that usually occurs on voluntary basis and delights the listener as it is for example by listening to music. On the other hand, noise is defined as an unwanted sound that may cause displeasure, annoyance and pain or, referring back to its word origins, nausea.

Investigations have shown that continuous noise exposure has an enormous damaging impact not only on hearing but also on the general health status of the population.

Although preventable, NIHL is one of the most widespread irreversible occupational diseases worldwide and thus was declared as a serious occupational hazard [4].

Several studies gave evidence that noise creates physical and psychological stress, commonly presented as reduced assessment, sleep disturbances, cardiovascular dysfunction and mental health alteration [5, 6].

The protection of health and safety from hazards at work should be our all interest. Therefore, our research is aimed at evaluating the impact of occupational noise on hearing, general security of health, quality of life and productivity of those working in stressful environments shown at the example of emergency service working personnel, who give constantly their best to protect and save our health during emergency.
