Most studies within the area of noise research have dealt with the impact of noise in residential areas. But the last decades there has been increasing awareness of the importance of protecting the special sound qualities of natural areas for the benefit of outdoor recreationists [1
]. While natural sounds are experienced positively even at loud levels, technological sounds are generally experienced negatively in natural settings [5
]. To escape from noise, and to experience the silence and peace of nature have been found to be among the most important reasons for visiting outdoor recreational areas [8
]. In studies that examine the impact of noise together with other potential area problems or disturbances, noise has been found to be among the most salient problems [10
The present paper presents results from a panel study, conducted as telephone interviews in connection with the relocation of Norway’s main airport in 1998. The old airport was totally closed down, while the new main airport was an existing airport that was expanded. A special issue of importance regarding the effects of an airport relocation is how the changes in aircraft noise exposure affect the experience in local outdoor recreational areas. While some studies have examined responses to various types of aircraft overflights in national parks and wilderness areas [11
], knowledge about effects in local urban or rural recreational areas are lacking, and especially knowledge about the effects of abrupt changes in noise exposure. The effect of the airport change on noise annoyance during single visits to nearby outdoor recreational areas was examined by cross sectional field studies that combined survey data with noise measurements [22
]. The panel studies that are presented here examine the more lasting impression of experiences in the study areas after a season of use before and after the airport change. To the best of our knowledge, this is the first panel study to examine experiential effects of both a decrease and an increase in overall aircraft noise exposure in outdoor recreational areas in the vicinity of commercial airports.
Commonly, the experiential effect of changes in noise exposure is assumed to be predictable on the grounds of dose-response relationships derived from data collected in a stable state situation [13
]. However, there are some indications from studies in residential areas that especially an abrupt change in noise exposure levels may cause people to “overreact” compared to the predictions made by steady-state dose-response relationships [26
]. The field data from the same recreational areas before and after the airport change were analyzed to test the influence of the situation of change on the dose-response relationship in an outdoor recreational setting [22
]. A strong effect of the situation of change was found, beyond what would be expected from data from before the moving of the airport. Several explanations of the change effect have been suggested in the literature on noise effects in residential areas [34
]. One possible explanation is that attitudes modifying the exposure-response relationship changes. For instance, overall opinion of the neighbourhood could change [34
]. The “overreaction” effect in terms of noise annoyance in the recreational areas might also indicate that the changes in noise exposure levels affect a broader set of experiential dimensions than “noise annoyance” alone. The main purpose of this paper is to examine how changed aircraft noise exposure possibly influences the experience of other area conditions, as well as the perceived overall recreational quality of outdoor recreational areas.
1.1. Review of the Literature
There are some indications in the literature that noise may affect a broader range of experiential dimensions. Perhaps most obviously, noise may interfere with the natural quiet of a site [11
]. But noise may also influence other aspects of the recreational experience, and detract from the experience and enjoyment of the visitors [11
An interaction effect of image and sound has been demonstrated in the perception of the general quality of landscapes. In an experimental study, Carles et al.
] let the subjects evaluate the pleasantness of six images and six sounds alone and in combination. The images were natural or semi-natural scenes, and urban parks. The sounds ranged from purely natural sounds to mechanical sounds caused by human activity. The evaluation of each stimulus (visual or aural) was found to be modified by the co-presence of another stimulus. The situations that were rated most positively were those where there was coherence between the visual and the aural stimulus. In a postal survey to visitors of wilderness areas Tarrant et al.
] found that overflights influenced visitor solitude and tranquillity more than annoyance. The effect measures were related to the single aircraft overflight that the visitors best remembered. Anderson et al.
] utilized three different experimental procedures for the assessment of the impact of different sounds on the aesthetic evaluation of outdoor settings. The subjects were either evaluating the sounds in a field setting, or both setting and sounds were described verbally, or they were presented to photographs and tape recordings. All three procedures produced similar results. While natural and animal sounds were found to enhance the evaluation of natural sites, technological sounds were found to detract from the evaluation of the sites. In another laboratory experiment Mace et al.
] examined the effect of helicopter noise on the evaluation of a natural vista. Slides were presented together with either 40 dB(A) or 80 dB(A) helicopter noise. These conditions were compared to a control condition where background natural sounds accompanied the slides. The presence of helicopter noise was found to adversely affect all dimensions that were evaluated in the study, which were: naturalness, preference, scenic beauty, freedom, annoyance, solitude, and tranquillity. An effect was found on all measures for both noise exposure levels, but the effect was most pronounced at the highest noise level. A comparison of the affect states before and after the experimental condition showed that positive affect states decreased while negative affect states increased significantly. The findings are mainly confirmed by later research [38
]. An experimental study examining the evaluation of different combinations of natural scenes and sounds found that the evaluations in terms of pleasantness primarily were differentiated by the sounds that accompanied the scenes, while there was little differentiation in the evaluation of the visual impressions [40
]. The effect, and the direction of the effect, may depend on the context, urban or natural, and basic expectations to sound and environmental qualities in the different settings [5
An interaction effect of visual and aural stimuli has also been indicated in the urban context. However, where the residential or urban setting is the basis for study, the influence of vision on sound perception, not the other way around, has mostly been focused. The opposite focus and findings in regard to the direction of the effect in studies of natural versus urban settings presumably are related to basic differences in setting functions, and what may be expected of sound, silence, and dominance of built or natural visual elements. In the natural setting, technological sounds are assumed to potentially adversely affect visual qualities, and thereby recreational benefits of the natural areas. A stress reducing effect of viewing nature is well established in the literature [42
], while noise is an ambient stressor that possibly might detract from this effect [37
]. On the other hand, in the predominantly built environment of the urban setting, natural landscape elements might reduce the stress caused by noise, compared to settings without natural elements. While most studies have focused on the positive effects of viewing nature, a recent experimental study also indicates that nature sounds facilitate recovery from stress [45
The first to explore the relationship between the visual and aural perception of the city was Southworth [46
]. Not focusing on noise, but on the general influence of sounds on the perception of the visual city, Southworth found that the aural and visual sensations mutually influenced each other in the impression of a particular site. He took subjects on trips around the city of Boston, and let them describe their experience in their own words. The subjects could either hear, but not see, or see, but not hear, or both see and hear. In regard to the perception of noise in the residential setting, the visual street aesthetic has been found to influence the degree of noise annoyance [47
]. People living in streets that were rated more highly on visual aesthetic quality (e.g., pretty/ugly, aesthetic architectonic appearance, greens) were found to be less annoyed at the same noise levels than people living in streets that were rated lower on visual dimensions. In a series of five experimental studies and two field surveys Tamura et al.
] examined the audiovisual interactions in the formation of annoyance of urban places. The results indicated that annoyance was based on a combination of auditory and visual conditions. First, the degree of tree plantations was found to reduce annoyance with traffic noise, and thereby annoyance of a space, or “the personal impression of feeling uncomfortable within the place”, as stated by Tamura et al.
]. On the other hand, there were also indications that the presence of plants might “awaken the feeling of annoyance” by the larger expectations to quiet that the plantation arouse. Another experimental study found that the influence of the visual context on the sound ratings depended on the type of sounds [41
]. The evaluations of bird song and traffic were negatively influenced by increasing degrees of urbanization in the visual stimuli. The ratings of human sounds did not depend on the context. In the experimental study of Anderson et al.
] cited above both natural and technological sounds were relatively neutral in regard to the aesthetic evaluation of the most urban settings. An effect was found when the visual stimuli contained natural elements. Although not consistent on all points, all the above cited studies point to an interaction effect between the perception of visual and sound stimuli, at least in some contexts and for some types of sound. The findings may be explained in terms of cognitive consistency theories [51
]. According to these theories, people tend to seek internal coherence in their evaluations of the various components of a situation. Simon et al.
] studied experimentally what happens in the process of reaching a verdict. They found that not only do various components influence the experience of the whole. In the process, the general impression also influences the perception of the parts. Cognitive consistency theories would predict that people would align their evaluations of different conditions to conform to a consistent representation of an outdoor recreational area. But also, that a general impression of change, to the better or the worse, could influence how various area conditions are perceived.
Aircraft noise is but one of several environmental factors that may detract from the recreational experience in outdoor recreational areas. Other environmental factors that have been found to be potential problems in outdoor recreational areas are for instance crowding, litter, damage to natural, historical, or cultural resources, development, and maintenance of facilities [11
]. These potential “annoyances” are usually examined item by item. However, on the background of previous findings and notions from cognitive consistency theories we propose that they may also be examined as visual or aural stimuli that might interact in their influence on the recreational experience. That is, the existence and perception of one factor might influence how the other is perceived. This would also mean that a change in noise exposure levels would influence a broader range of experiences than noise annoyance alone.