Correlation Between Acoustic, Luminous, Thermal Dimensions of an Urban

Park in an Oasis Settlement and Emotional Response of Visually Impaired

Users

Samiha Boucherit 1 Department of Architecture and Industrial Design, University of Campania "Luigi Vanvitelli" Via San Lorenzo, 81031 Aversa (Italy) Massimiliano Masullo 2 Department of Architecture and Industrial Design, University of Campania "Luigi Vanvitelli" Via San Lorenzo, 81031 Aversa (Italy) Djihed Berkouk 3 Department of Architecture, Biskra University Biskra 07000, (Algeria) Luigi Maffei 4 Department of Architecture and Industrial Design, University of Campania "Luigi Vanvitelli" Via San Lorenzo, 81031 Aversa (Italy)

Abstract

Occupants' interaction with urban spaces and their behavior is often influenced by environmental dimensions: thermal, visual, acoustic or air quality. Many studies have investigated the relationships between occupants' behavior and these dimensions, but just few of them have addressed occupants with special needs, such as the visually impaired. This study, based on measurements' campaign and research activities conducted at Biskra (Algeria) inside an urban park in an oasis settlement, provides further investigations about the relationship between acoustic, luminous, thermal dimensions and the emotional response of visually impaired users as a basis for validating and improving their wellbeing in important spaces of the urban environment such as the public parks. The methodological approach is based on both quantitative and qualitative assessment. The objective study is based on evaluating the physical dimensions of the site, while the subjective one is based on conducting in-situ questionnaires such as a multi-items Likert scale and multi-sensory evaluation towards the environment. Findings obtained from this study could offer a new vision to planners and designers to improve the wellbeing of visually impaired users by including the multisensory dimensions as constitutive elements of architectural, urban and environmental projects.

1 samiha.Boucherit@unicampania.it 2 massimiliano.masullo@unicampania.it 3 d.berkouk@univ-biskra.dz 4 luigi.maffei@unicampania.it

ites 2022

1. Introduction

The perception of the world is multisensory where all the senses work harmoniously at the same time. These senses can overlap with each other in the context of influence and effectiveness [1-4] but it is worth mentioning that space perception involves multisensory processes, including both vision and hearing, which are the two important means of defining objects in the abstract space [5]. The sensory system transmits the information given by the physical environment to the mind's realm so that it can be interpreted and perceiving the surrounding environment [6].

In the last decade, in the built urban contexts, sound and visual environment design have attracted the attention of lots of researchers. Despite this, there are still limited solutions to assist professionals in developing projects which consider the multi-sensory perception and urban planning is still considered a huge challenge for them. This limitation is more and more evident if we consider certain categories of individuals, such as the visually impaired people who are not able to build spatial patterns that require visual sense [7, 8]. However, these persons use natural proprioceptive patterns and some kinds of exteroceptive schemes as tools to understand the space [5].

In recent years, studies aiming to understand the relationships between all the multisensory inputs and the urban environment have been conducted. These studies provide an interesting viewpoint on the exploration of aesthetical preference [9] and environmental satisfaction [10]. In our previous paper [11], it was reported a preliminary study aimed to receive information such as the physical characteristics of two open spaces (Street March 08 and Landon park) in the city of Biskra in Algeria (see Figure 1a) and subjective qualitative assessment of visually impaired users. A series of in situ measurements was carried out, in March 2021, by measuring the different acoustic, thermal and luminous dimensions in the 30 stations distributed in the study area (see Figure 1b). Complementarily, this new study intends to verify the correlations among the physical dimensions characterizing the environment of Landon park, the perceptual and emotional, as well as the multi-sensory evaluation of visually impaired individuals.

Figure 1. Case study (a) Localization of the city of Biskra, (b) on-site measurement stations [11]

2. Methodology

The methodological framework of this research is based on both, on-site measurements and on-site subjective surveys. This approach allows comparing the descriptors which characterize the physical dimension of the environment with the human dimension.

2.1. Material

On-site measurements included recordings of thermoigrometric (Air Temperature, Ta; Mean Radiant Temperature, Tmrt; Relative Humidity, RH; and Wind Speed, Va), visual (illuminance, E; and Sky View Factor, SVF), and acoustics (Sound pressure levels and percentiles) indicators. They were used to calculate Noise Climate (NC), Physiologically Equivalent Temperature (PET), average luminance (Avg. Lum), and Daylight Glare Probability (DGP).

The on-site subjective survey consists of two different questionnaires: the first focused on the emotional salience of sounds [12], where, using a 9-point Likert scale (1 = Not at all; 9 = Extremely), participants were asked to rate how much the sounds they heard were … (Pleasant, Unpleasant, Stimulating, Boring, Attractive, Unattractive) and how much the sounds they heard made them feel…”: (Calm, Nervous, Weak, Energetic, Happy and Sad); and the second which investigates the multi-sensory dimensions of human-park interaction. This questionnaire investigates different and multisensory components of the interaction between individuals and park: Nature and Vegetation, Thermal comfort, Acoustic comfort, Visual and touch comfort, Olfactory comfort, Uses and feeling. During the survey 52 school pupils (6-18 years old) belonging to a special school for visual impairment, suffering from diseases and visual impairments, were involved. None of them had hearing problems. Recruitment and testing were in accordance with the Declaration of Helsinki and participants gave their consent before taking part in the study.

Figure 2. Methodological framework.

3. Results

Results of the on-site measurements [11] show that Tmrt ranged between about 41°C and 55 °C, and that for the 83.3% of the measurement stations the thermal sensation of the occupants was considered warm, or higher, with a PET value greater than 28°C. The glare of outdoor daylighting resulted imperceptible to park occupants who have normal vision, DGP values range

between 0.018 and 0.392, while the sound equivalent levels between the different measurement stations of the park ranged between 46.5 and 57.5 dB(A) (st. dev. ± 2.9). 3.1. Correlation among the physical dimensions of the environment

Table 1 shows the correlations between SVF and the physical dimensions of the environment (thermal, luminous, and acoustic dimensions). In particular, regarding the thermal dimension no significant correlations between SVF and Tmrt nor PET emerged. This is in accordance with the work of Karimi et al. who confirmed that SVF is not a proper indicator for determining the thermal comfort conditions and indicators [13]. As expected, for the physical dimensions of the luminous environment, Table 1 shows the existence of significant correlations between SVF and DGP and also the average luminance with ( p -value = 0.01) and a correlation coefficient of 0.723 and 0.878, respectively [14]. Regarding the acoustic dimension, no significant correlations were observed.

Table 1. Pearson correlation between SVF and physical dimensions (thermal, luminous, and acoustic

dimensions)

Tmrt PET DGP Avg. Lum Leq NC SVF Corr. 0,325 0,128 0,723 ** 0,878 ** 0,225 0,065 Sig. 0,079 0,500 0,000 0,000 0,233 0,732 * The correlation is significant at the 0,05 level (two-tailed). ** The correlation is significant at the 0,01 level (two-tailed).

Table 2 summarizes the correlations between the thermal dimensions (Tmrt and PET) with luminous and acoustic dimensions. Table 2 shows that there is a significant correlation between Tmrt and PET with a correlation coefficient of 0.763 and ( p -value = 0.000) [15]. Moreover, no significant correlation was observed between both thermal dimensions (Tmrt and PET) with luminous and acoustic dimensions (DGP, Average Lum, Leq, NC), where the p-value is greater than 0.05 for all cases.

Table 2. Correlation between thermal dimensions and luminous and acoustic dimensions PET DGP Avg. Lum Leq NC Tmrt Corr. 0,763** 0,287 0,269 -0,295 -0,136 Sig. 0,000 0,124 0,151 0,114 0,473 PET Corr. 1 0,201 0,183 -0,329 -0,171 Sig. 0,286 0,334 0,076 0,367 * The correlation is significant at the 0,05 level (two-tailed). ** The correlation is significant at the 0,01 level (two-tailed).

The correlations between the luminous dimensions (DGP and Average Lum) with the acoustic dimensions are presented in Table 3. Table 3, shows that there is a very strong significant correlation between the DGP and the average luminance value with a correlation coefficient of 0.912 and a p-value equal to 0.000. Likewise, Table 3 also illustrates the absence of significant correlations between luminous dimensions (DGP and Average Lum) and most of the acoustic dimensions where no correlation was observed ( p -value> 0.05).

Table 3. Correlation between luminous dimensions and acoustic dimensions. Avg. Lum Leq NC

DGP Corr. 0,912** 0,069 -0,184 Sig. 0,000 0,716 0,330 Avg. Lum Corr. 1 0,155 -0,108 Sig. 0,415 0,871

* The correlation is significant at the 0,05 level (two-tailed). ** The correlation is significant at the 0,01 level (two-tailed). 3.2. On-site subjective survey results

The on-site subjective survey aimed to collect data both on the occupant's living conditions in outdoor spaces and on their emotional responses, in relation to the sound, thermal, odors and luminous environments [11].

3.2.1. Acoustic salience of the sound environment

Results of the two components of the acoustic salience of sound environment show that the subjects describe the sound environment as Pleasant (M pleas =6,6) and Attractive (M attr =6,6). Less evident was the value assigned to its character to be Stimulating (M stim =5,9). On the contrary, negative attributes were very low, especially for the Boring (M bori =1,2) and Unattractive (M unatt =1,5) (Fig. 3, left). Considering the emotional component of the scale the environment makes subject feel very happy (M hap =6,7), but also calm (M calm =5,9) and energetic (M energ =5,9). Negative attributes are consistent with positives (M nerv =2,1; M weak =2,7; M calm =1,8) (Fig. 3, right).

Figure 3. Perceptual (left) and Emotional (right) components of the acoustic salience of the sound

environment

3.2.2. Multi-sensory evaluation of human-park interaction

Table 4 shows all the items associated with the six components of the Multi-sensory survey. For each of them, the average rating and standard deviation are presented.

The visually impaired users, although their young age and lack of experience, recognize the strong presence of vegetation in the park and its connotation as a nature site. They are also able to recognize the influence of the shaded areas on the global thermal comfort and specifically on the sensation of cooling, coherently with the measured data (SVF=0.208).

Table 4. Multi-sensory evaluation towards the environment: Nature and vegetation, Thermal comfort,

Acoustic comfort, Visual and touch comfort, Olfactory comfort, Uses and feeling

Components N Items Mean Score

St. Dev.

1 The park is home to a variety of plants 9,38 1,40 2 The land is rich in vegetation 9,27 1,62 3 The grass is suitable for spreading out 6,83 3,73 4 You can easily get in touch with nature 9,17 1,49

Nature and

vegetation

4 The park has areas shaded by plants 9,54 1,05 5 I come to the park to stay cool 8,60 2,79 6 The park is sunny 6,00 3,76

Thermal

comfort

7 In the park, you can hear the sounds of nature 9,56 1,51 8 In the park, there is a nice music background 7,94 3,72 9 Inside the park, musicians or singers perform 4,37 4,09 10 In some places, you can hear the flow of water 8,92 1,84 11 The park is a quiet place 8,69 2,26

Acoustic

comfort

12 In the park the noise of the vehicular traffic is absent 5,48 4,32

13 In the park, you can hear the children playing 8,37 3,23 14 There are parts of the park that are a bit noisy 6,92 3,58

15 The park paths feature beautiful textures 8,58 2,39 16 Water is used as an ornamental element 8,92 2,19 17 The flooring is comfortable and you can walk 8,02 2,71 18 There are enough places to sit 7,79 2,24 19 The seats are comfortable 7,38 2,78

Visual and

touch comfort

20 In the park, you can feel the scents of nature 8,81 2,40 21 There are no particular smells in the park 5,13 4,11

Olfactory

22 In the park, you can smell bad smells caused by the presence of waste 2,62 3,63

comfort

23 In the park, there are bad smells caused by vehicular traffic 1,92 3,16

24 Inside the park, I relax and stop to reflect 7,73 3,32 25 In the park, I can interact with other people 8,40 2,73 26 In the park, I do physical activity 6,63 3,86 27 In the park, I dedicate myself to artistic 4,02 4,25 28 In the park, I like to spend time with my family 8,83 2,32 29 I use the park for jogging or walking outdoors 7,87 3,30 30 In the park, I feel at peace and I am very well 9,17 1,58 31 When I'm in the park I have a feeling of 9,38 1,45 32 In this park, I feel at ease and I feel connected 8,98 1,73 33 I am attracted to this place. I will go there again 9,12 1,72 34 I feel safe in the park 9,52 1,09

Uses and

feeling

Most of the visually impaired people's movements in the park rely on their sense of touch for pattern perception and to identify the differentiation of the textures [16]. They are able to identify through the sense of touch and appreciate the comfort of design elements such as seats and they are particularly sensitive towards the olfactory comfort confirming that the blind and visually impaired have greater practical smelling ability than the normally sighted people [17].

As expected, their hearing sense is pronounced and permits them to clearly and easily distinguish between natural sounds and mechanical sounds but also to appreciate the park as a quiet place. This component of the multi-sensory survey is coherent with the evaluation of the acoustic salience of the sound environment and with the measured data (Leq index does not exceed the noise level standard of a public green open area of 50 dBA [18]).

4. Conclusion

The emotional response and the wellbeing of young visually impaired users of an urban park have been investigated by measuring physical dimensions and in contrast conducting an in-situ survey questionnaires campaign specifically on the perceptual and emotional acoustic salience of the sound environment and, in a more general way, on a multi-sensory evaluation of the sites and their experience.

The results of this study confirm that the visually impaired, even at a young age, have the ability to interact with the surrounding environment in a multi-sensory manner that is not affected by the absence of sight [19] and that their reactions are congruent with the physical dimensions. This congruency leads to a better acceptance of the public space.

On the basis of these abilities and experiences, designers of public spaces should consider the importance of the multisensorial approach for the success of the design of public spaces.

5. Acknowledgements

The authors would like to thank the responsible persons, the teachers, and the students of the School for the Visually Impaired in the city of Biskra for their support in conducting this research study.

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