"Effects of nocturnal aircraft noise on sleep " in the DLR-Project "Quiet Air Traffic I"
Investigation of Subjective Sensation Based on Questionaires
Compared to unwanted sound, no other environmental stimulus leads to the same kind of annoyance and disturbance reactions, which can produce disturbances of the psychical, physical and social human (well-)being. In the sociological and psychological research concerned with the effects of noise, persons affected by aircraft noise about feeling disturbed or annoyed by it are examined by using either questionaires or free interviews. Noise annoyance is usually connected to feelings of irritation and discomfort, as it interrupts or interferes with a desired activity. Annoyance by aircraft noise results primarily from disturbance of communication, rest and relaxation and sleep. Interruptions of nocturnal sleep are among the most usual reasons of noise-induced complaints today.
In the STRAIN studies, specific questionnaires for the research of psychological effects of nocturnal aircraft noise are used, which measure so-called secondary reactions to aircraft noise (e.g. assessment of sleep quality and sleep frequency, unacceptability and strength of the nocturnal aircraft noise; general disturbances by aircraft noise). Standardized questionnaires from psychological research are also applied in order to measure changes of subjective health, strain and recovery due to aircraft noise exposure. A survey of a possible impairment of recovery is important because nocturnal aircraft noise presumably diminishes an important resource for recovery processes - sleep. All measured subjective psychological aspects are put in relation to physical aircraft noise parameters (e.g. maximum level LASmax, number of flight events) to describe dose-response-relationships between acoustic stimuli and the resulting reactions and to define the corresponding "critical" limit values. It was especially important for the selection and construction of the instruments used that they be sensitive enough to measure even minor changes, as the results can be expected to be relatively small due to the short span of the study. Preliminary to the studies, the non-acoustic moderators of subjective noise reactions (e.g. preliminary noise strain, personal attitude to the noise source, noise sensitivity and extent of the preliminary noise strain by aircraft noise, features of the living situation) known to noise effect research will already be determined and taken into consideration in the analysis.
In the STRAIN laboratory investigations, the advantages of laboratory and field studies have been combined already, as the subjects were able to lead their "normal" lives with all its manifold requirements by day -i.e. the subjective processes examined are being assessed realistically. On the basis of the current field study, we are also going to verify in how far the results obtained in the laboratory apply to the facts of the natural setting of the concerned persons.
The interdisciplinary structure of the studies enables us to establish relationships between electrophysiological, performance-related and psychological data and to gain indications for a mediating role of psychological components on physiological reactions.
Further Reading on "Subjective Perception" at this point