Effect of Nocturnal Aircraft Noise on Psychological Stress Indicators

Abstract:

As part of the DLR-Project „Leiser Flugverkehr“ (Quiet Airtraffic) the effects of nocturnal aircraft noise on the experience were investigated by means of three identically designed laboratory studies. Altogether 96 subjects, including 16 subjects submitted to the control condition , spent 13 nights each in a laboratory facility. The subjects under experimental conditions have been exposed to aircraft noise during the night varying in number and volume, after they got us ed to the setting during two nights.

According to the cognitive coping-theory, a model of psychological and physiological effects of nocturnal aircraft noise was developed: Annoyance was no longer regarded as a mere reaction variable but as a mediator between the physical noise parameters and psychological stress indicators. In addition, some relevant social-demographical and psychological variables were inserted as moderators.

Psychological stress indicators are operationalized following current concepts of modern bio-psychological and strain and recreation research. Mood as stress indicator was measured by the MDBF: multidimensional mood questionnaire (“Mehrdimensionalen Befindlichkeitsfragebogen”) in the morning and in the evening. Strain and recreation processes during the day were measured by the EBF: strain and recreation questionnaire (“Belastungs- und Erholungsfragebogen”) in the evening. Furthermore the relations were investigated to indicators of level o f action (tests of performance) and level of physiology (hormone-state in urine collected over night) as well as level of personal experience (self-rated sleep quantity and quality).

The results of the study indicate a slight decrease of mood (regarding the dimensions mood and alertness) and recreation (especially for sleep), as well as a small increase of strain (regarding performance and somatic aspects). The effects are mainly due to the number of aeroplanes and secondary to the equivalent sound level pressure. The maximal sound level is the most unimportant predictor for analysed psychological after effects.

Data indicating prolonged effects of aircraft noise at night are not found. Only a small influence of the self-rated impairment on psychological after effects depending on nocturnal aircraft noise at home appears. Furthermore a slight effect of demographical and psychological moderators is given. Controlling these moderators, the relations between the psychological stress indicators and the noise parameters persisted.
Regarding other stress indicators, only weak relations between the level of cortisol excretion and some parameters of performance resulted. Semi-sized relations to the self-rated sleep parameters were found too.

The most important result was, that direct effects of aircraft noise at night on the psychological stress indicators are just marginal. However clear effects appear when considering the mediation of annoyance. These effects are also more extended and prolonged compared to the direct impact of the acoustical parameters. It can be concluded that nocturnal aircraft noise only clearly effects mood, strain and recreation, if persons are annoyed by it. Furthermore, conclusions regarding dose-response-relationships can be given taking annoyance into account.

This survey was conducted to prove psychological stress reactions as comparatively short after effects of aircraft noise at night by means of a valid measurement of the constructs ‘mood’, ‘strain’ and ‘recreation’ with respect to their variability and multi-dimensionality. Therefore, further statements regarding the explanation of psychological mechanisms can be made if merely considering annoyance. These results, however, must be proven by those examined during field studies. Furthermore, data obtained from a fourth laboratory study are needed to specify the relations in the documented model.