Exposure to high or low frequency noise at workplaces: differences between assessment, health complaints and implementation of adequate personal protective equipment (PPE)
K.Reinhold*, S.Kalle and J.Paju Institute of Business Administration, Tallinn University of Technology, Ehitajate tee 5, EE12618 Tallinn, Estonia
Abstract
Employees are exposed to high and low frequency noise which may cause different health effects. Hearing loss first occurs in the high frequency range, low frequency usually causes sleeping disturbances and annoyance. TES 1358 sound analyzer with 1/3 octave band was used to measure the equivalent sound pressure level, the peak sound pressure level, and the noise frequency spectrum at different workplaces. All the results were compared to Estonian and International legislations. High frequency noise was studied in metal, electronics and wood processing industries. The results showed that in several cases, the normative values were exceeded and the highest values appeared in the range of speech frequencies. Frequency analysis indicated that the noise level spectra at work stations of various machines differed in patterns. The low frequency spectra on a ship showed peaks in the frequency range of 50...1,250 Hz. Most employers provided workers with personal protective equipment against noise, but when selecting ear muffs, noise frequency had not been taken into consideration and therefore workers in the same enterprise used similar ear muffs. Knowledge of the prevailing frequencies assists to decide which ear protection should be used to avoid damage. An adequate hearing protector device can reduce the noise exposure significantly. Key words: Noise, frequency analysis, PPE, occupational hazards.
INTRODUCTION
The human perception of sound is between 20...20,000 Hz. The ear is most receptive in the range of 500...8,000 Hz, so called acoustical window, even though the most sensitive range of hearing is 1,000...4,000 Hz (Salvendy, 2012) and the spectrum of human speech ranges in the frequency region of 250...6300 Hz (Cox & Moore, 1988). Health effects from noise exposure have been studied by many researchers. Differences in complaints between low (20...500 Hz) (Alves-Pereira & Castelo Branco, 2007) and high frequency noise have been presented in several sources. Also it has been indicated, that hearing loss tends to occur in the range of high frequencies first (Salvendy, 2012). Industrial noise can mainly be characterized with high frequency noise, but also a considerable number of workers are exposed to low frequency noise on a daily basis. There is a general agreement that progression in hearing loss at frequencies of 500, 1,000, 2,000, and 3,000 Hz eventually will result in impaired hearing, i.e. inability to hear and understand speech (Johnson et al., 2001).
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