The aim of this study was to set up a statistical measure for determine the total cumulative noise exposure of Finnish conscripts (n = 1,054) as a result of leisure-time noise activities. All of the conscripts underwent hearing screening. The conscripts' time in noisy activities and their rating of the loudness and estimated noise levels of the activities were used as the predictors in the risk analysis. Self-reported hearing symptoms (i.e., tinnitus, pain in the ear) and hearing loss due to noise exposure were also inquired about. Twenty-seven percent of the conscripts had weekly noise exposure to > 85 dBA. Approximately 20% of the conscripts had >20 dB hearing loss in either ear in the frequency range of 0.5 to 8 kHz. The incidence of hearing symptoms seemed to correlate with an increased noise dose.

The aim of this study was to arrive at a theoretical statistical measure for the possible risk of future noise-induced hearing loss (NIHL) due to leisure time activities in teenagers. The subject's time consumed in noisy activities, the subject's self-evaluated loudness of the activities and estimated noise levels were used as the actual predictors in the risk analysis. Symptoms of hearing damage, i.e. tinnitus, pain in the ear and temporary hearing loss due to noise exposure, were also inquired about. No measurements of hearing loss were carried out in this study. Fifty-one percent of teenagers were estimated to be exposed to noise levels detrimental to hearing acuity. The incidence of hearing symptoms seemed to be correlated to increased noise dose. The noisiest leisure activities were: playing in a band, motor sport, discos and pop-concerts, and shooting. The results give indications of possibilities for NIHL among teenagers.

SummaryDuring daily care, laboratory animals are exposed to a variety of sounds which may have effects on welfare and also cause physiological and behavioural changes. So far, almost no attention has been paid to individual sounds or the sound level caused by animal care or the sound level inside the animal cage. In this study, sounds from selected rat care procedures were recorded: pulling cage out of the rack, placing it onto a table and replacing the cage back into the rack; with measurements made inside the rat cage and in the adjacent cage. Diet was poured into the food hopper and sounds were recorded inside the cage and also the adjacent cage. The work was repeated in a calm and also in a hurried style, using stainless steel and polycarbonate cages. Finally, the sounds produced by running tap water were recorded. Differences between rat and human hearing were compared using novel species-specific sound level weightings: R-weighting for rats dB(R) and H-weighting for human dB(H). Hurried work with steel caused sound exposure levels exceeding 90 dB(R) when the cages were placed into the rack and about 80 dB(R) when pulling them out of the rack or placing onto a table. With polycarbonate, the levels were 10-15 dB(R) lower. Unhurried calm working produced lower sound exposure levels than hurried working in many procedures. When the procedures were repeated with measurements in the adjacent cage, the sound exposure levels were lower, but the results were similar. Pouring food pellets into a hopper above the rat's head caused 15 dB(R) higher sound exposure levels than pouring food to an adjacent cage. In general, humans hear these sounds about 10-15 dB louder than rats. In conclusion, cage material, working style and hearing sensitivity all have an impact on the sound exposure level in the rodent cage. With correct working methods, high sound levels can be efficiently avoided in most cases.

This study presents an evaluation of the total cumulative noise exposure of Finnish conscripts (N = 416) during military service. All of the conscripts underwent a hearing screening and filled out a noise exposure questionnaire at the beginning and end of their military service. Eighty-nine percent of the conscripts were exposed weekly to military noise of over 85 dBA during the service. Eighteen percent of the conscripts had already reached at the end of their military service a cumulative noise dose corresponding to noise exposure of 85 dB for 40 years. During military service, permanent hearing loss of > 20 dB in the frequency range of 0.5 to 8 kHz increased from 19 to 27% among the conscripts.

No abstract