Aircraft noise-induced annoyance in the vicinity of Cologne/Bonn Airport - The examination of short-term and long-term annoyance as well as their major determinants

In the light of a continuously growing air traffic and a presumably resulting impairment of the quality of life of airport residents, the present doctoral thesis aims at the extensive investi-gation and description of short-term and long-term annoyance induced by aircraft noise in the vicinity of Cologne/Bonn Airport, Germany. This thesis was written in the framework of the European project COSMA (Community Oriented Solutions to Minimise Aircraft noise annoyance). A telephone study with 1,262 residents (M = 58.6 years, SD = 15.5, 61.8 % female) as well as an in-depth study in the field with further 55 residents (M = 45.7 years, SD = 14.3, 61.8 % female) were conducted. On the basis of these results, an attempt was made to identify measures to reduce community annoyance. The telephone survey in summer 2010 focused on the examination of the status quo of community annoyance due to aircraft noise during the past 12 months (= long-term annoyance). Likewise, the study aimed at the identification of the key variables that determine the annoyance judgment in addition to the equivalent continuous noise level. A further purpose of the telephone survey was the preparation of the subsequent field study conducted in summer/autumn 2011. The telephone survey was run in six areas exposed to an equivalent aircraft noise level between 40 and 55 dB(A). The aircraft noise exposure of the examination areas was oper¬a-tionalized by the A-weighted energy equivalent sound pressure level (LAeq) for the six busiest months of the year. The LAeq-values were extracted from a current noise contour map. Since at Cologne/Bonn Airport air traffic, and in particular freight traffic, is operated also at night, not only the general annoyance but the annoyance at night, i.e., between 22:00 and 06:00 hours, was examined as well. Aircraft noise-induced annoyance was assessed by means of a semantic five-point scale recommended by the International Commission on the Biological Effects of Noise (ICBEN). In addition, an open format question was applied to gain information about times of day when the aircraft noise is particularly annoying. Diverse personal and situational factors were examined regarding their effect on annoyance. In a multiple-stage process using the multiple linear regression approach, a prediction model for aircraft noise annoyance was developed both for general and night-time annoyance. A comparison of the annoyance data obtained in the vicinity of Cologne/Bonn Airport to the European standard exposure-response curve clearly indicated an increase of the percentage of highly annoyed individuals at a given noise level. Respondents reported particular high annoyance due to aircraft noise for the late evening and night. The variables found to signifi-cantly contribute to long-term annoyance ratings comprise the LAeq as well as the following non-acoustical predictors: a) the belief that the airport could take actions to improve the residents’ situation, b) the perception of negative aspects of the local airport and air traffic, c) carrying out measures to cope with the noise, d) the general attitude towards the airport, e) the satisfaction with the residential area, f) the respondent’s environmental conscience, g) the general sensi¬tivity to noise as well as h) the degree of urbanization of the investigated areas, and i) the presence and evaluation of domestic noise insulation. Night-time annoyance was predicted by the same variables as general annoyance and the size of the effect of the single predictors was compa¬rable. The ten predictors explained 54.8 % of the variance in the general annoyance ratings and 52.3 % of the variance in the night-time annoyance ratings. Whereas a number of prior surveys focused on the examination of long-term annoyance due to aircraft noise, only very few studies examined short-term annoyance in the field. There-fore, the main purpose of the in-depth field study subsequent to the telephone survey was to inves¬tigate the contribution of a wide range of acoustical parameters and non-acous¬tical factors to aircraft noise-induced annoyance during the preceding hour. Further¬more, the field study aimed at the examination of the relation between daytime short-term annoyance, subjective sleep quality, and long-term annoyance. In addition, within the frame¬work of the present field study, the construct fairness that has been investigated mostly in the organi-zational and legal context by now was introduced to the context of aircraft noise exposure and annoyance in the field. The field study was run in two areas with an equivalent aircraft noise level above 50 dB(A). Over four days and nights, the sound pressure level was logged continuously. Thereby, 30 acous¬tical parameters could be derived. Besides prominent noise indicators, such as the LAeq, the number of aircraft noise events, or the maximum level, parameters were calculated which have not been considered thoroughly in previous field studies on annoyance. In particular, person¬alized parameters were included that take into account the outdoor levels as well as the attenuation due to the partic¬ipant’s whereabouts (outdoors vs. indoors) and different window positions. Simultaneously to the level recordings, participants repeatedly rated their annoy¬ance due to aircraft noise in the interval of one hour. Short-term annoyance in the preceding hour was assessed at daytime between the time the individuals got up and the time they went to bed. For the annoyance assessments, the semantic five-point scale recommended by the ICBEN was used that had been implemented in a stand-alone application on a netbook. Situational factors, such as the time of day and the activity carried out in the past hour, were ascertained in the course of these hourly assessments, too. In addition, the partici¬pants rated their subjective sleep quality for each of the four study nights. Further personal and rather time-invariant variables as well as the long-term annoyance due to aircraft noise in the past 12 months were surveyed in a supple¬mentary face-to face interview. Generalized Estimating Equations were applied to esti¬mate the impact of the acoustical parameters and non-acoustical factors on one-hour annoyance ratings. Several prediction models for short-term annoyance were developed and compared according to their model fit. The relation between short-term and long-term reactions to aircraft noise was assessed using the multiple linear regression approach. For the examination of fairness in the context of aircraft noise exposure, a new questionnaire was developed and evaluated. Three dimensions of the construct (distributive, procedural, and informational fairness) plus a global fairness judgment were tested on their correlation to long-term aircraft noise annoyance. The model which predicted short-term annoyance ratings most precisely contains the person¬alized LAeq for aircraft noise during the past hour, the number of aircraft noise events in total, and the number of aircraft noise events above a threshold of 70 dB(A). Moreover, this model considers the activity carried out mostly during the past hour, the respondent’s general sensitivity to noise, and the presence and evaluation of domestic noise insulation. A moderate relation was found between the average one-hour annoyance rating across the four study days and the general annoyance during the past 12 months. Furthermore, the field study results revealed that the contribution of the average subjective sleep quality during the study nights to long-term annoyance is equal to the contribution of the average short-term annoyance at daytime. The results of the fairness questionnaire showed that residents of Cologne/Bonn Airport perceive the allocation of aircraft noise and the airport-related decision-making as only slightly fair. The general belief that one is treated fairly with respect to aircraft noise was related higher to long-term annoyance than the score for any of the three fairness dimensions. The findings of the telephone and field study stress the importance of the number of aircraft noise events besides the LAeq as well as the impact of personal and situational factors for the prediction of aircraft noise-induced annoyance. Whereas for long-term annoyance, the influence of the personal factors is prevailing, for short-term annoyance, the situational and acoustical variables are decisive. Furthermore, the findings suggest that the long-term annoy-ance rating does not reflect merely an average rating across several different noise situ¬ations. With regard to the status quo of community annoyance due to aircraft noise, the conclusion is that the current European standard dose-response curve needs to be updated as it seems to underestimate the percentage of highly annoyed residents. Moreover, the results emphasized the high contribution of nocturnal annoyance and disturbance due to aircraft noise to general long-term annoyance. For a reduction of the community annoyance, not only acoustical and operational aspects of the aircraft noise exposure should to be improved. Likewise, a candid and truthful communication between the profiteers of the air traffic and the airport residents exposed to the noise needs to be estab¬lished to enhance the acceptance of the air traffic in the vicinity of the airport.