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Survey and Aims of the Study

The study STRAIN (Study on human specific Response to Aircraft Noise) that investigates the effects of nocturnal aircraft noise on humans is divided into six study sections. For four representative sleep facility studies, 32 subjects per study will be divided into 4 groups of 8 subjects and exposed to aircraft noise under controlled, but realistic conditions for 13 consecutive nights. During the study nights in the isolation facility AMSAN, the test subjects will be exposed to aircraft noise events (take-offs and landings) with changing maximum levels and at frequency of occurence distributions as well as different temporal patterns while sleeping. Here, physiological reactions as well as the subjective perceptions of the test subjects the next morning will be registered. The first two nights serve the purpose of habituation to the conditions of the laboratory. The following nights, the subjects are exposed to aircraft noise events. There also are control groups that will not be exposed to aircraft noise for the complete 13 nights. The four laboratory studies are structured as double-blind studies (neither examiners nor volunteers know if, when or what kind of aircraft noise the volunteers will be played back in the night) in a cross-over design (there are control groups and the grade of the aircraft noise strain in the other groups is distributed in a random way). Control variables are gender, age and prior aircraft noise annoyance. Further demographic data are raised from the volunteers in order to be able to further classify the results after the evaluation.

The criteria established by the laboratory study will be tested in two extensive field studies. A total of 128 subjects in the sleep facility and 64 subjects "in the field" (i.e. at their homes) will be examined in approx. 2500 nights. As the sleeping behavior differs highly between different individuals, this high number of test nights is necessary in order to be able to make certified statistic assertions about the influence of nocturnal aircraft noise - in relation to control variables - on the human body and mind.

The sleeping behavior of children, teenagers, elderly and ill persons differs clearly from that of healthy persons of normal hearing aged 18 to 65 years. In order to be able to obtain statistically significant and scientifically tenable results about these subgroups, it would be necessary to examine a far higher number of nights. This would exceed the framework of this study, which will end in 2003. Furthermore, the study is not structured clinically-epidemiologically. Acute effects of nocturnal aircraft noise will be examined as far as possible here.


Frequently Asked Questions:

Arent't there enough studies about this topic already? 

At present, there are only a few studies about "effects of nocturnal aircraft noise on human beings" in which electro-physiological variables like the EEG and the ECG have been recorded. The 2500 nights to be recorded in this study will add twice the amount to the 1200 test nights using polysomnography recorded globally up to now. In the majority of the past studies, the physiological data were compared only to the Leq (=equivalent permanent sound level, see acoustics) of the night's noise events. However, the simultaneous recording of noise stimuli and electro-physiological reactions is a basic condition for the assessment of of physiological reactions to acoustic stimuli. In this study, the temporally coordinated coupling (temporal resolution is at up to five milliseconds) enables us for the first time world-wide to accomplish an accurate event-correlated evaluation of sleep disturbances due to noise events.

There are, however, many studies measuring the subjective perceptions by means of questionnaires. There are results from questionnaire evaluations of about 30-40 000 subjects world wide.


Which scientific questions will be answered by this study?

• The study will examine the direct, immediate reactions of human beings to nocturnal aircraft noise. It will concentrate particularly on the effects on sleep, performance, fatigue and the grade of inconvenience and/or strain.
• By means of the reaction mentioned above, the study will throw a light on the relevance of permanent sound level, maximum volume and frequency of noise events.
• The study will create a new, extensive and detailled database that will be determined and developed by means of homogeneous methods under laboratory and field conditions.
• The study will consider possible differences in reactions regarding age, sex, prior subjective noise annoyance and other social characteristics.
• Besides producing new conclusions, the study will supplement older, less extensive and methodically insufficiently complete studies.
• The study will compile fundamental criteria which could enter e.g. the amendment of the legislation for the regulation of nocturnal aircraft traffic. 

• This study is NOT epidemiologically structured. It will therefore not be able to show DIRECT connections between aircraft noise and illnesses or sociological changes occurring on a long-term basis.
• The study will not consider effects on e.g. infants, children, pregnant women or sick persons. 

What is the current state of the project?

4 Laboratory Study Units
			Autumn 1999
			Early Summer2000
			Spring 2001
			Spring 2003
2 Field Study Units
			Autumn 2001 - Spring 2002
			Spring 2002 - Autumn 2002
Total of 192 volunteers, 2500 nights, 18-65 age, of both genders, healthy according to age and of normal hearing
			128 Volunteers in the sleep facility (June 2003)
			64 Volunteers in the field (November 2002)