Hygienic Assessment of Low Frequency Noise Annoyance in Working Environments

Abstract

Different ways of assessing low frequency noise below the level of hearing damage to predict noise annoyance are treated. Three methods for classification of low frequency noise are tested. Some assessment methods, e.g. low frequency noise ratings (LFNR), frequency weightings A - D, the difference dB(C) - dB(A) and Zwicker loudness, are presented and evaluated regarding their relation to rated annoyance. Low frequency noise groups were selected out of 338 recordings from different occupational environments, e.g offices, laboratories, manufacturing premises, etc. The annoyance ratings were made on a graphic rating scale. The annoyance ratings corresponding to the recordings were correlated to the different low frequency noise measurements. Correlations between different low frequency noise measures and annoyance ratings are presented. None of the methods that are evaluated seems to fit better than the others for assessment of low frequency noise annoyance. A conclusion drawn is that when assessing low frequency. noises, the usual methods should be handled with care.

A Study on the Relationship between Subjective Unpleasantness and Body Surface Vibrations Induced by High-level Low-frequency Pure Tones

“…in the 25-to 50-Hz range). This disagreement was consistent with many previous studies which have reported that the A-weighted sound pressure level is insufficient for evaluating lowfrequency noise 11,12,[14][15][16][17] . The correlation coefficient calculated for the 'best-fit' frequency-weighted sound pressure level (SPL W ) is also listed in Table 2.…”

“…However, it is well known that low-frequency noise often causes unpleasantness or annoyance 7) . These adverse psychological effects can be induced even by low-level low-frequency noise in living environments 8,9) and they are expected to be more prevalent in working environments where high-level low-frequency noises are generated [10][11][12] . Inukai et al 13) reported that the slopes of the equalunpleasantness level contours are very similar to those of the equal-loudness level contours.…”

“…This finding indicates that hearing sensation plays an important role in perceiving unpleasantness or annoyance of persons exposed to lowfrequency noise, despite the low audibility of the noise. However, there have been many studies reporting that considering the A-weighted sound pressure level, which is standardized on the basis of the human equal-loudness level contours, is insufficient for evaluating annoyance caused by low-frequency noise or noise with strong low-frequency content 11,12,[14][15][16][17] . These studies imply that some other factors, in addition to the loudness, contribute to inducing unpleasantness or annoyance caused by low-frequency noise.…”

LFN and the A-Weighting

“…where a, b, and are numerical constants (Vos, 2001) The expression (C-A)>15 has been widely used as an identifier of LFN (see Holmberg et al 1997) With the above in mind, an equation has been derived for LFN, and is put forward as follows; L = A + (0.84A-29.44) + 0.04(C-A)(41-A)…”

Parameters involved in low-frequency noise annoyance

“…Different assessment methods; low frequency noise ratings (LFNR), frequency weighings A -D, the difference dBC -dBA methods and Zwicker loudness, have been evaluated regarding their relation to rated annoyance (Holmberg et al 1996). According to the results, the correlations between annoyance and weighted values, linear values, sone values and the dBC -dBA difference are poor, None of the methods seemed to fit better than the others for assessment of low frequency noise annoyance.…”