The results of earlier studies attribute acute stress reactions to nocturnal aircraft noise, but do not contain detailed information on the adaptive and habituation processes during the exposure. This question was followed up with an experimental longitudinal study at Hamburg's Fiihlsbiittel airport. The test persons were exposed to nocturnal electroacoustically simulated aircraft noise in their apartments. Recorded among other things was the personal health condition, cortisol excretion collected through the night and daily collected subjective data. After the initial cortisol reaction (increasing in the first days) the course of cortisol excretion is not uniform. The results suggest that adaptation to nocturnal aircraft noise is specific to the sex. Beside these sexually specific differences there are considerable individual differences both for women and men. We found three fundamental adaptation types in agreement with results of animal experiments. From a preventive medical point of view two of the adaptation types, i.e. increasing cortisol excretion and decreasing cortisol excretion, are accompanied with health hazards. The increasing cortisol excretion exceeds the normal medical range in the process of adaptation. The decreasing cortisol level can be identified as "protective inhibition". The majority of the men can be classified in the first mentioned adaptation type. From this knowledge it can be concluded that noise-induced health risk for men is to be estimated as essentially higher than for women.

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This study assessed the effect of other safety gear worn in proximity on the attenuation afforded by earmuffs attached to a hard hat. Seventy-two males and females participated: 24 under the age of 40 years with normal hearing, and 48 over the age of 40 years, half with normal hearing and half with bilateral high-tone hearing loss. Measurements were made with the ears unoccluded, with the muffs on hard hat alone, and with the muffs on hard hat in combination with safety glasses, an air-purifying half mask respirator or both glasses and respirator. They included (1) diffuse field hearing thresholds from 0.25-8 kHz, and (2) consonant discrimination in quiet and in 80-dB SPL speech spectrum noise. Attenuation was derived by subtracting the unoccluded from the protected hearing threshold at each frequency. Muff attenuation was within 6 dB of the manufacturer's specifications but decreased by as much as 5 dB when the glasses or respirator were worn and by 9 dB with both these devices. Males achieved 3 dB higher attenuation than females. However, hearing status had no effect. Consonant discrimination was significantly worse in noise. The impaired subjects performed more poorly when wearing the muff on hard hat but there was no additional effect of wearing the glasses and/or respirator. These results demonstrate that wearing other protective safety gear around the head can interfere with the hearing protection provided by earmuffs. They also confirm that for people with a hearing loss, the use of earmuffs may increase the communication handicap.

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Objective: To determine the association of occupational noise exposure and blood pressure in a group of workers at the metallurgical plant. Methods: Noise exposure at the workplace and blood pressure were measured in 178 male workers of steel mill company. Criteria for including in the study group were: age below 35 years, employment-exposure duration longer than 3 years, hearing threshold level in normal range and no cardiovascular history. Program of examination included: individual questionnaire, ORL - examination, tone audiometry, measure of weight, height and blood pressure. Cigarette smoking, diet habits and other risk factors of elevated blood pressure were controlled. Noise exposure was assessed for each work place, by means of direct and indirect measurements. Results: Systolic blood pressure was statistically significantly higher in the group exposed to the higher noise levels and the results of multiple regression analyses revealed a significant relationship between the occupational exposure to noise and systolic blood pressure. No such relationship with diastolic blood pressure was found. Conclusions: The results suggest the positive association between occupational exposure to noise and blood pressure.

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The possible relation between aircraft noise exposure and the prevalence of complainants around Schiphol airport was studied. The home address of people who complain about aircraft noise at the Environment Advisory Committee Schiphol was combined with annual average noise levels, using a Geographic Information System. The prevalence of complainants in areas with different noise exposure was calculated. In addition, data from a questionnaire survey was used to gain insight into the influence of sound insulation, personal characteristics, and aspects of health on complaint behaviour. The prevalence of complainants increases from < 1% at 50 dB(A) (L _den ) to about 7% at 62 dB(A). Above this level the prevalence drops back to < 3%. An increase in the percentage of sound insulated houses with increasing noise levels is observed, rising markedly above 60 dB(A) (from 24% to almost 90%). When comparing people who complain with those who do not complain about aircraft noise, complainants report more noise annoyance (OR=10.2, 95% CI=8.54-12.3), sleep disturbance (OR=9.87, 95% CI=8.19-11.9), concern about health (OR=8.02, 95% CI=6.75-9.53), and fear for an aircraft crash (OR=3.64, 95% CI=3.07-4.31). Results indicate a relation between aircraft noise exposure and the prevalence of complainants, possibly influenced by sound insulation. Important determinants of complaint behaviour apart from noise level are noise annoyance, sleep disturbance, concern about health, and fear for an aircraft crash. Although complainants do not seem to be representative for the total population, and do not reflect the full extent of noise annoyance, their prevalence does reflect the regional distribution of aircraft noise annoyance in a noise polluted area.

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The aim of this study was to determine a statistical measure for total weekly noise exposure from leisure-time noise activities in a Finnish urban adult population. The subjects´ time consumed in noisy activities, and their self-evaluated loudness of the activities converted into equivalent noise levels of the activities were used in the calculation of weekly noise exposure levels. Self-reported hearing symptoms (i.e., tinnitus, pain in the ear) and hearing loss due to noise exposure were also asked with the questionnaire. No measurements of sound level or hearing loss were made in this study. Forty-one per cent of subjects were estimated to be exposed to noise at levels over 75 dBA, and 9% of the subjects had weekly exposure that was over 85 dBA. The incidence of hearing symptoms seemed to correlate with increased noise dose and age. The noisiest leisure-time activities were going to night-clubs and pubs, using home tools, playing in a band or orchestra, shooting and attending or participating in motor sports.

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The measurement of urinary free cortisol is an established index for the diagnosis of disorders involving glucocorticoids (see Braun et al. 1999) but the amount of free cortisol in urine samples is dependent on the analytic-technology. Competitive binding assays and radioimmuno assays, the methods used most commonly in routine laboratories, missestimate the amount of free cortisol because of interference by strongly cross-reacting substances in urine (Schoneshofer et al. 1986b). The specificity of these tests is too low to distinguish between free cortisol and near metabolites. The revision of the long-term study by "online" liquid chromatography (HPLC) suggestes that immuno assay technique produce doubtful results, particulary when free cortisol and metabolites react in different ways. This is of particular importance, since several studies containing indications, that an acute demand leads particularly to alterations of free Cortisol and a chronic demand essentially to alterations of metabolites. Schoneshofer pointed out already in 1986 that by additional measuring of the 20α-Dihydrocortisol and Cortisone it may be possible to differentiate chronic hypercorticoidism from the acute state. In connection with the findings of the present comparison it is urgently required to standardize both the data collection and the data analysis to get comparable results. Therefore, it has to be concluded from today's point of view, that free cortisol and metabolites must be investigated with HPLC if urine samples are used.

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