Introduction
Since the introduction of the “soundscape” concept by R.M. Schafer in the 1970s [1], many projects, e.g., the COST Action “Soundscape of European Cities and Landscapes” [2], and studies have dealt with the perception of the acoustic environment in a context, that is considering the interrelationships between person, activity, and place, in space and time. Thus, soundscape research is a step forward in noise control, as it does not conceive noise per se but rather reconceives the conditions and purposes of its production, perception, and evaluation, accounting for a human-centred point of view [3]. For this reason the soundscape approach treats the acoustic environment as a multi-dimensional entity composed of several audible sources, some of which enhance and others diminish the effects on overall soundscape quality [4]. In 2003, Lercher and Schulte-Fortkamp reviewed the relevance of soundscape research for the assessment of noise annoyance at the community level [5]. The soundscape approach can provide new insights into the existing annoyance data and new holistic research strategies having as a central issue the improvement of the relationship between the “aural space” and the living environment [3].
An interesting application of the soundscape approach deals with parks, particularly those in urban areas. Because Nature plays a vital role in human health and well-being, parks play an essential health-promoting role by providing individuals access to Nature [6,7]. Indeed, parks can help individuals recover, at least temporarily, from stress [8], and they offer opportunities for relaxation from the noise pollution to which the population is exposed in daily life. Unfortunately, urban parks are often surrounded by noisy areas due to the sound emission of road traffic, industries, and other sources. The extent of the park has an important influence on the tranquillity that can be achieved due to effects of distance in reducing traffic noise emanating from the boundary roads and the provision of a high percentage of natural features [9].
Awareness of the preservation and improvement of the environment quality in urban parks is increasing, as also addressed by the European Directive 2002/49/EC on the assessment and management of environmental noise [10], which, among its objectives, requires the preservation of environmental noise quality where it is good.
The studies adopting the soundscape approach in analysing the acoustic environment in urban green areas have been increasing in the last few years; for instance, see [4,11–16]. Among the several outcomes, good soundscape quality was found to be achieved if the road traffic noise exposure is below 50 dB(A) during daytime [4]. The importance of masking by natural sounds, such as sound produced by water [17,18], in improving the quality of the city park soundscape has also been reported [13]. Considering the non-acoustic factors, the reasons for coming and the activities carried out in the park have been shown to influence the perceived restoration achieved [12,19].
In Italy, there are few studies on city parks. The first investigation available in literature on the soundscape in urban parks was performed in three green areas in Naples [20]. The study found that noise levels were greatly influenced by the traffic on the surrounding busy roads, and the reported annoyance was also influenced by the subject’s expectation of hearing a sound in a specific environment.
The present study is an extension of the investigation carried out in Naples [20], as it was carried out using a similar experimental protocol, but the questionnaire used for the interviews to park users
was modified and expanded on the basis of the previous experience. In particular, self-assessment of noisiness perceived at home and at workplace was added to investigate the influence of these environments on the ratings given on the other items. Measurements of the acoustic environment were performed in five parks in Milan. These parks differ from those in Naples because of the socio-cultural and climatic context and because the answer options provided for questions dealing with non-acoustic factors were different. The set of acoustic data and subjective ratings was more extensive than the investigation in Naples, and the statistical analysis was carried out in greater detail.