VARIOUS PRESENTATION OF NOISE PERCEPTION IN BYDGOSZCZ GREEN AREAS

Urban green spaces effectively regulate the microclimate [1, 2] and significantly contribute to air purification in cities. The quality of life observation and measurement of human perceptions and objective environmental indicators are essential for the proper evaluation of urban green areas. City dwellers live far away from the natural environment. It causes a high demand for services provided by urban green areas. Parks in cities are the basic source for human health and quality of life [3, 4] and indicate the necessity of studying the perception of this type of environment. A proper presentation of the results helps to manage the green spaces.

The maps showing the area of noise pollution are a useful tool used in urban planning. They provide information about acoustic perception. Based on the literature, it can be assumed that the soundscape maps contain three different themes: a sound source map, a psychoacoustic reception map, and a perceptible quality of the sound environment [5, 6, 7]. The soundscape map informs about the perception of different types of noise, including positive ones. The reception map determines the sound perception. Together with the perceptible quality of the sound, the environment creates a special acoustic map like a mental map or a fuzzy cognitive map. Liu et al [8] describe a map of sound sources perception on the basis of spatial-temporal variability. He divided sources into: anthropological, biological, geographic, and showed that they are characteristic of urban spaces and depend on their compositions. Mental maps show the relationship between the human perception of individual characteristics in their environment. Using the mental maps in spatial planning helps to arrange these areas in the right way [9]. Another way to present fuzzy information is fuzzy cognitive maps. They show the relations between the components shaping the studied areas. Possible scenarios are, to some extent, guidelines for improving existing conditions (e.g. acoustic) [10, 11, 12]. Acoustic space shaping consists in forming the right acoustic conditions that the sound stimuli do not exceed permissible values from the point of view of health and a human activity. These factors should guarantee creation and maintain the acoustic comfort. The acoustic comfort should provide acoustic conditions that do not exceed the permissible values. These levels for the described area should not exceed 68 dB (L_DEN – traffic noise). However, from the point of view of the noise impact on a human, the permissible value is 65 dB (L_AeqD – traffic noise). The acoustic comfort is described in the papers with the range from 20 to 55 dB [13]. And, according to the subjective tests of the National Institute of Hygiene, full acoustic comfort is up to 50 dB [14]. Thus, the aim of this paper is to present the possibility of using mental maps in the recognition and presentation of visitors’ feelings in Bydgoszcz selected recreational and rest areas.

Figure 1.

The analysis of sounds perception was conducted in two Bydgoszcz parks located in Śródmieście District (Figure 1).

These are urban parks for rest and recreation. The location in the city center causes greater exposure to the noise of people staying there. The first research area is Jan Kochanowski Park located in the western part of Śródmieście District. Created in 1901, it is an example of English style and was designed by Konrad Neuman. The area of the park is over 3 hectares.

The traffic noise is the dominant source of sound in Jan Kochanowski Park. This is due to the border with the streets: from the west – January 19^th 1920, from the north – Adam Mickiewicz Avenue and from the east – Ignacego Jana Paderewskiego Street. Because of the bus stops at the edge of the park, the noise produced by these vehicles is compounded by the stopping and restarting buses.

The second research area is the oldest park in Bydgoszcz – Kazimierz Wielki Park (Casimir the Great Park) (2.24 hectares). This space is located in the central part of Śródmieście District among the streets: Konarskiego, Gdańska, Jagiellońska and Freedom Square.

Traffic intensity on street sections adjoining the analyzed areas during the day is as follows (based on ZDMiKP Bydgoszcz data ): –

Gdańska Street-trams 190, cars 988,

The acoustic climate of the north, south, and west of the park is mostly influenced by car and tram transport on the streets. Because of the direct proximity of a secondary school, the park is the place where many youth groups spend their free time, especially during the breaks. There is also a playground.

To present the prevailing acoustic climate in the park, the questionnaires were carried out among the visitors to these areas. These studies give the answer to the question of how people perceive sounds. This is important information that may be used in the development of such areas. Mental maps of sound perception with noise types were made on the basis of the respondents’ answers. The respondents also designated the sources of noise, which was the base for the implementation of fuzzy cognitive maps.

Noise sensitivity depends on the sound characteristics and the recipient (age, state of health, mood, sensitivity and psychological resistance). Specified sounds can simultaneously cause impressions that can be pleasant and annoying. There are several sources of infiltrating and emitting noise in the study area. The external sources include traffic, and, in one of the parks, the Philharmonic neighborhood. The internal sources include children’s playgrounds and park visitors.

In the Polish legislation, the acoustic map is the basic document in the noise protection. The acceptable noise level in the daytime (traffic noise), as an equivalent sound level L_AeqD, is 65 dB in recreational and leisure areas. Figure 2 presents the acoustic map and traffic noise penetration inside the parks, and then, the noise indicator is LDEN and permissible value is 68 dB.

It can be seen that there is the penetration of traffic noise inside the parks. The range is from 55 dB to 70 dB (Jan Kochanowski Park – neighboring Mickiewicza Street). However, other sources of sound have also an influence on acoustic comfort.

Figure 2.

Because the acoustic map concerns a long-term noise protection policy, in order to present the current noise in the park, the measurements of the equivalent sound level were made for the time of a day in the spring and summer season (selected days before noon and aftenoon). On the basis of the results, the geometric means were calculated to obtain the noise values in the areas of parks. At the same time, the surveys carried out among park visitors gave the answer to the question about the noise sources.

As a result, the following mental maps of the analyzed parks were made. This method allows to single out the source of a perceived sound and the direction of the sound (Figures 3 and 4).

The noise located in the park is influenced by outer and inter sources. For selected parks, the most important sources are: –

the number of visitors (inter source),

On the other hand, the improvement of the acoustic space is affected by the greenery. Finally, these components affect the health of people residing in the area.

In the further analysis, the Mental Modeler program was used. It enables the qualitative assessment of incidents affecting, in this case, the acoustic comfort of selected areas. On the basis of the information expressed in descriptive terms (in questionnaires – the noise from roads, visitors number and the greenery, added “human health” as a factor depending on the noise emitted.), a fuzzy cognitive map was made. As a result, it is possible to build scenarios that increase or decrease factors influence on the soundscape in parks. The scenarios are presented in diagrams with a non-quantized axis in the range (-1; 1). This is the relationship (correlation) between the analyzed factors. The scenario analysis can be an output for the decision-making processes in the field of noise protection.

Figure 3.

Figure 4.

Figure 5.

The fuzzy cognitive map allows visualizing the relationship between individual components. For the analyzed areas, the resulting relationships are presented in Figure 5.

The processes shown in Figure 5 are based on the beliefs and experiences of people visiting parks and allow predicting environmental dependencies. To see how the factor change may affect other components, two scenarios were made (Figures 6 and 7).

Figure 6.

Analyzing Figure 6, it can be noticed that the greenery increase in the described parks causes a drop in the noise coming from the outside, and it has a positive impact on the visitor’s health and the number of visitors.

However, when limiting car traffic (Fig. 7), one can observe a significant noise decrese in the park with a simultaneous increase in the number of visitors and a beneficial effect on their health. Cities are the composition of separate, non-homogeneous areas. People build their perception. In his work, Soja [16] sees people as active components in the creation and interpretation of space. The soundscape is the concept of how people perceive, experience or understand the acoustic environment [6]. To determine this space well, it should know its purpose. The study of spatial activity and movement allows widening the process of constructing social space and the relationship between the perception and the space [16, 17, 18]. In the park, the acoustic comfort as the relationship between the sound, the environment, and the people were presented by Tse et al. [20]. In addition to the visual assessment of the landscape, the acoustic comfort created an important role in the acceptance of the city park. The sound must be measured and evaluated by people [17, 21]. Therefore, the measurement procedures have to be related to the perception of the human environment. The best way to test people’s feelings is a survey [6]. Many authors describe the need for such studies to determine the quality of the sound space. Not to focus on individual dimensions or sound components. It refers to the general perception of the acoustic environment, in the “good” or “bad” soundscape [2, 4]. The proper poll allows receiving answers about subjective sound responses. On this basis, the perception of sounds can be visualized by means of mental maps or fuzzy cognitive maps.

Figure 7.

The analysis of the surveys showed: –

the noise in the city park areas is troublesome – 53%,

The greater impact on the acoustic climate formation in these areas has the traffic noise entering the parks. There can also be seen the influence of noise coming from another source, the inside of the parks – the visitors. The respondents in the survey identified the directions of the sounds flow and defined their subjective “intensity”.

The right soundscape is now an important determinant of recreational and leisure areas. The aim of the paper was to present the possibility of using mental maps in the cognition and presentation of visitors feelings in the selected Bydgoszcz parks. The green area protection from noise pollution has already been discussed in the earlier publications. Then, the research object was the health spa park and it focused on determining the relationship between the measurements and the feeling. It has been shown that the perception of noise by people is different from the measurements [22]. In this paper, the mental maps and the fuzzy cognitive map of two Bydgoszcz parks were made on the basis of the survey results.

The conclusions of the work are as follows: –

the soundscape is created by all the sources in the area,

These conclusions show the necessity of an individual approach to shape such spaces in terms of noise emissions. The lack of planning documents and descriptions that allow a specific way of managing and using the park space has an impact on their acoustic quality.