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Hearing and Noise
Published in Stephan Konz, Steven Johnson, Work Design, 2018
A pure tone is a one-frequency sound. Most industrial noise is a mixture of frequencies known as broadband noise. If the frequencies are equally distributed throughout the audible range, this is known as white noise, which sounds like rain.
Sound and Vision
Published in Skip Pizzi, Graham A. Jones, A Broadcast Engineering Tutorial for Non-Engineers, 2014
A pure tone has a single frequency, known as a sine wave. Figure 3.1 illustrates this graphically, as a plot of sound pressure level against time. Typical natural sound is more complex, and is made up from many individual sine waves of different frequencies and amplitudes, all added together. The mixture of different sine waves determines the shape of the wave and the character of the sound we hear.
Effectiveness of hearing protection apparatus in preventing noise induced vestibular loss
Published in International Journal of Environmental Health Research, 2022
Süha Ertugrul, Emre Soylemez, Tuğçe Gurel
Ramakers et al. (2016) investigated the effect of earplugs on temporary hearing loss and tinnitus in their studies. The hearing of 51 individuals who attended the outdoor music festival were evaluated using a pure tone audiometry test, and distortion product otoacoustic emission test (DPOAE). The severity of tinnitus was evaluated with a questionnaire. It has been reported that individuals who do not wear earplugs have more temporary threshold shifts at 3 and 4 kHz in pure tone audiometry tests compared to individuals who wear them, and that these individuals have a decrease in DPOAE amplitudes between 2–8 kHz. In addition to temporary hearing loss, it has been stated that wearing earplugs also prevents tinnitus that occurs after excessive noise. Hong et al. (2013) investigated the prevalence of wearing HPAs among 425 firefighters and compared the hearing systems of firefighters wearing and not wearing HPAs. In the study, the average HPAs wear rate was only 34% of the time needed, and approximately one-third of the workers did not wear HPAs at all. Besides, the authors found that the risk of hearing loss increased with the increase in working time and decreased with the length of time of wearing HPAs. In our study, we evaluated the hearings of 81 workers in the metal industry using a pure tone audiometry test. Thirty-seven of these workers (45.7%) stated that they always wore HPAs, 18 (22.2%) stated that they sometimes wore HPAs, and 26 (32.1%) stated that they did not wear HPAs at all. There was no difference between these workers in terms of working time in the metal industry. In our study, similar to the study by Hong et al. workers who constantly wear HPAs had better PTAs than workers who sometimes wear HPAs and not at all. There was also no difference in terms of PTAs between workers who sometimes wore HPAs and those who did not. HPAs wearing time is an important factor for the effectiveness of HPAs and can directly affect NRR. For example, studies have shown that if HPAs with 20 dB NRR are not used for 30 minutes in an 8-hour working shift, the NRR will decrease by 5 dB (Berger 1980). Therefore, in our study, workers who stated that they sometimes wore HPAs did not benefit effectively from wearing them.