*3.2. Sound Perception of the Blind Older Adults*

3.2.1. Sound Perception Model Development

1. Open coding

This study did the open coding, which is the process of coding data line by line and conceptualizing and categorizing them, and breaking, crushing, and re-integrating them through continual comparison [64]. The 25 sets of raw data from the first interview were summarized to the level of concepts and categories, as shown in Table 2. The initial extraction of memos was carried out, resulting in 74 labels (aa); then, the 74 labels generated 22 initial concepts (a) through the process of grouping the labels with the same content into one concept; finally the results obtained from the conceptualization were re-refined, resulting in nine initial categories (A).During the iterative process of comparing the categories, three core categories emerged, in terms of the sound perception of the blind older adults in nursing homes: "sound requirements" (A2, A5, A6), "acoustic environment" (A3, A7, A8), and "sound cognition" (A1, A4, A9).

**Table 2.** Open coding scheme of the sound perception.


\* The rest of the labels are detailed in Appendix A, Table A1.

### 2. Selective coding

After the core categories were preliminarily determined, the data obtained for the second time underwent selective coding. In the process, only the content related to the core categories of the blind older adults' sound perception in nursing homes was encoded [65]. As shown in Table 3, three new initial concepts were extracted and grouped into the categories of "sound perception" (a1, a2, a23), "sound source setting" (a12, a20, a24), and "sound context" (a22, a25); no new core categories were created.

#### 3. Theoretical coding

This study also did the theoretical coding, to organize the implicit relationships between the categories formed in the process of substantive coding to build a theory [66]. In this study, three core categories of sound requirements, acoustic environment, and sound cognition were identified in the substantive coding process, and these core categories were found in a recursive relationship: first, the blind older adults obtain a basic understanding of

are nearby

sound from the starting point of their living needs; then they feel the acoustic environment of nursing homes from the perspective of the living environment, and finally; they perceive the acoustic environment from the dimension of sound cognition in combination with contextual memory. The sound perception model of the blind older adults in nursing homes is shown in Figure 6.

**Table 3.** Selective coding scheme of the sound perception.


\* Bolded parts are newly-emerging codes.

**Figure 6.** Sound perception model of the blind older adults in nursing homes.


Participants in the interviews indicated that sound was a vital ingredient in their daily lives, helping them to access information about the language and the environment, to avoid danger, and to be a constant companion and a major means of entertainment. However, sound, for example noise, may interfere with the life and rest of blind older adults. In addition, some participants stated that "I need a quiet environment when I speculate (aa23)", "Blind people make more noise than normal people, so we need a separate space (aa26)", and "We need to hear the outside world to make sure we are in a social environment (aa73)". They also emphasized that "The sound insulation of nursing homes should not be too good, otherwise it will block old residents' calls for help (aa11)". It can be seen that the sound requirements of the blind older adults vary with the demands of life.

#### 2. Acoustic environment

It was found that he acoustic environment influenced the sound perception of blind residents through the room allocation, sound source, and loudness setting in nursing homes. Since the blind older adults relied on the acoustic environment to understand and remember their current living environment [13], nursing homes created sound sources at particular points to convey key messages. For example, some staff members stated, "The sound of music broadcast makes it easy for the residents to determine their position relative to the building as they walk around the outdoor circular walkway, and can help them remember roughly how many laps they have taken (aa77). The music broadcast is not played in the winter when older adults will go out less (aa83)". However, one resident stated that "Broadcast sound is too loud and affects the judgement of orientation (aa47)". Therefore, the sound source setting and loudness design need to complement each other to achieve the best possible delivery. In addition, some participants would like to have "more audible warnings in public showers (aa79), in places difficult to walk (aa22) and when others pass by (aa50)", and some stated that "Some places have prompt sound but I don't know how to turn (aa66)". These statements revealed the problems existing in the set-up of sound sources used to suggest the routes and warn of dangers in the acoustic environment of the nursing home which needs to be optimized.

The allocation of rooms by the managers was also found impact the acoustic environment of the nursing homes. For example, some participants felt that "the eastern part of the home is too noisy". It may be because the east side of the nursing home is close to the traffic road, or may also be due to the managers placing in the east the senior residents who tend to make more noise because of their hearing loss and reduced mobility. However, a noisier environment is not necessarily bad, for some blind residents expressed their preference to a livelier environment. Therefore, conducting relevant investigations would benefit optimizing the layout of the acoustic environment and reasonably allocating rooms for the residents of nursing homes.

#### 3. Sound cognition

The analysis revealed that sound cognition in the nursing homes was related to sound perception, soundscape memory, and sound context in minds of blind older adults. Wang investigated the acoustic demands in facilities for the elderly, and found that the most common unwanted sounds in general among older adults were people talking and other noises [67]. In the current study, most of residents interviewed expressed their understanding and acceptance, even though they often sensed the talking sound of others and felt the noise in the nursing home. And some residents interviewed even considered the sound of people talking a blessing stating that "We chat together in a good atmosphere (aa61)", and "There are sounds that will feel lively (aa89)". Since talking can be used to avoid loneliness [68], talking sound can make blind older adults feel that they are in a social environment.

The subjective preferences, personal history, and life experiences of the blind older adults produce different subjective perceptions of sound, and some perceptions were

combined with the scene at the time to form a soundscape memory [35]. However, there are individual differences in soundscape memory. Taking traffic sounds as an example, some residents felt "fearful of traffic sound (aa10)" and "annoyed by the sound of traffic signals (aa6)". However, some reported that "hearing traffic sound makes us feel safe (aa59)", "the sound of cars means that people are nearby (aa90)", or "traffic sound makes me feel that we are living in a busy urban area (aa74)". Therefore, in designing the soundscape to optimize the acoustic environment, the blind residents' sound perception and soundscape memory and the context in which the sound is represented, need to be seriously considered. The reasonable control in the soundscape dimension and the enhanced soundscape design would enhance the health and well-being of the blind older adults living in nursing homes.

#### **4. Discussion**

#### *4.1. The Relationship between Behavior, Sound, and Space*

According to the behavioral findings in Section 3.1, the daily behavioral activities of blind older adults in nursing homes can be categorized into basic living activity, leisure activity, social activity, and physical activity [56]. As shown in Figure 7, firstly, the basic needs of the blind older adults were met in the care unit (living) and the multifunctional hall (food) in the nursing homes; secondly, their leisure and recreation generally occurred in their personal care units or activity rooms, while social activities mostly occurred in the multifunctional hall, outdoor space, and others' care units; finally, the physical activities occurred in the outdoor space and public circulation of the nursing homes.

**Figure 7.** The relationship between behavior, sound, and space in nursing homes.

In this study, human, equipment, and environmental sounds were revealed as common sound sources in nursing homes [52,69–73]. Some of these studies found that staff sound was a major sound source in nursing homes, accounting for, for example, 26% [69] or 34% [72] of the total sound. However, the current study revealed that the staff members at the nursing home had already tried their best to avoid making noise around blind older adults so as to not confuse the information, as one staff member stated that "staff greet each other with as little noise as possible (aa78)". In addition, the nursing homes set up the informational sound at the spatial nodes to provide assistance for the blind older adults, and blind older adults were more dependent on electronic devices for leisure activities. The nursing home that we investigated had more informational and equipment sounds, and fewer staff sounds, than ordinary nursing homes. In conclusion, the daily behavioral activities of the blind older adults generated the massive human sound; the building site environment brought the environmental sound to nursing homes; as such, the normal operation of nursing homes and the equipment and machinery supporting the residents produced equipment sound. And the architectural spaces of the nursing homes helped the blind older adults accomplish the daily life behavioral activities, and these sounds were both indispensable and unavoidable. Meanwhile, exploring the sound perception of the

blind older adults in nursing homes helped to understand the impact of these sounds on blind residents.

#### *4.2. Comparison with the Soundscape Framework from ISO 12913-1*

Firstly, Figure 8 shows the differences between the sound perception framework of the blind older adults developed in this study and the ISO soundscape framework. On the one hand, sound not only conveys verbal information and carries recreational activities, but also helps blind people orient, remember, and recognize things. It is a complement to the lack of vision [74,75] and a crucial tool for blind people to perceive the external world. On the other hand, sound may also interfere with the daily activities and rest of the blind older adults, such as noise. Noise can cause not only mental health problems, such as irritability, insomnia, and depression, but also physical health problems such as tinnitus, dizziness, heart disease, and cognitive impairment [76]. Miller systematically reviewed the effects of noise on people and suggested that older adults need a less noisy environment for both communication and sleep [19]. Harris found that adding noise into reverberant conditions resulted in significantly poorer speech recognition in older subjects than in younger subjects [77]. Maschke et al. examined the effected of noise on people of different ages and found that the background noise affects the comprehension of older people about conversation [78]. Moreover, the residents may feel annoyed, when exposed to noise, thereby causing various negative emotions. Noise annoyance, as a major effect of noise, was revealed as a multifaceted psychological concept, including behavioral and evaluative aspects [79]. The blind older adults, therefore, need some sound sources to meet their demands, and avoid the interference caused by unwanted sound sources. In contrast to others, the sound requirements of the blind older adults have to be fulfilled. As for the undesirable sounds, from the perspective of the building users, they presented their response to noise, suggesting the importance of noise prevention and rule constraints. The nursing homes could meet the resident needs for noise prevention and control by reducing noise at the sources (e.g., aa42. purchasing silencing devices), blocking means in transmission (e.g., aa7. closing doors and windows), using sound masking at reception (e.g., aa8. playing sounds to mask other sounds), or adding human intervention (e.g., aa28. establishing management rules and aa48. exercising self-regulation). Moreover, from the perspective of designers, they may consider slope construction, plant greening, water features, and noise barriers around the building site, to block environmental noise from the outside and utilize the internal partition walls indoors to isolate equipment noise and materials such as acoustic cotton, acoustic panels, and felt to retrofit care units with poor sound insulation.

Secondly, some of sound requirements of blind older adults can be fulfilled with the acoustic environment of nursing homes. Since different building materials and reverberation times can indicate changes in the surroundings or space for blind residents, designers can help blind older adults understand their location by varying the reverberation time and footstep echoes caused by changes in the space volume, height or floor material, which managers of nursing homes may add to the interior nodes of nursing homes the wall plants or small ornaments such as wind chimes and birdcages, to create beautiful sounds for blind residents and help blind older adults make orientation judgments. In addition, as for acoustic environments, some designers are more focused on controlling the physical parameters of sound, while others intend to use ideal sounds to create a good acoustic environment [61]. The blind older adults put forward their needs for sound and the acoustic environment from the perspective of users, providing a new design direction for designers. As for the acoustic design of the living environment of the elderly or the disabled, especially the visually impaired, the should reasonable room layout, the sound insulation measures and the special needs of users should also be considered.

**Figure 8.** Differences between the sound perception framework of blind older adults and the ISO soundscape framework [31].

Thirdly, the acoustic environment describes the sound and defines the environment from the level of energy, while the soundscape mainly discusses people's perception of sound energy at the psychological level [80]. People's perception of sound depends on the acoustic environment, their attention, current activities, expectations, and prior knowledge [81]. Soundscape represents the relationship between people and the acoustic environment [82]. Similarly, sound perception refers to auditory sensation in ISO's soundscape framework in this study. Since blind people use known information to form mental maps [83] to support action [13,84,85] and hearing is involved in the perception, processing, and evaluation of information along with mental processes [86]; the soundscape memories forming during this mental process become part of the interpretation of auditory sensation. Furthermore, they are influential factors in the soundscape perception of blind older adults along with the sound context. Therefore, designers can add musical fountains, running water and plants to create a soundscape suitable for the site conditions, for the following reasons: the fountain has strong plasticity and can adapt to different sizes, and the running water can produce a signature sound of linear space. Moreover, plants can not only block the noise, but also create a good auditory feeling with wind or rain, and additional bird feed trees can be planted at the peripheral green belt of nursing homes attracts birds, for the songs of bird can increase the layers of natural sound. In sum, these strategies can be applied to enrich the soundscape layout of nursing homes.

#### *4.3. Limitations*

First, only one all-blind nursing home was investigated in this study, and thus the study based on this one case may not be comprehensive enough to explore all aspects of the issue. Second, this study focused on the subjective perception of blind older adults, without considering the physical environment, building materials of nursing homes, and the influence of the building interior decoration on the acoustic environment. Future studies may explore the complex relationship between the physical environment and sound perception of blind older adults living in nursing homes.

#### **5. Conclusions**

This study explored the relationship between space, behavior, and sound through on-site observations and semi-structured interviews in the only all-blind nursing home in China, investigating the sound perception of the blind older adults in the nursing home, and developing a model of sound perception.

The daily behavioral activities of blind older adults in the nursing home can be categorized into basic living activity, leisure activity, social activity, and physical activity. The architectural spaces of the nursing homes help the blind older adults accomplish the daily life behavioral activities the sounds of nursing homes are both indispensable and unavoidable. The dominant sound sources that can be perceived inside the nursing home included human sound, equipment sound, informational sound, and environmental sound. The daily behavioral activities of the blind older adults generated massive human sound; the nursing home produced the informational sound to support the mobility of the blind older adults; the normal operations of nursing homes and the equipment and machinery produced equipment sound; the building site environment brought environmental sound into nursing homes. And the blind home had more equipment sound and less staff sound than other types of nursing homes, for it needs informational sound to provide location information for blind residents.

The blind older adults' perception of nursing home acoustics consists of three levels: sound requirements, acoustic environment, and sound cognition. Firstly, the blind older adults highlighted their needs for sound and their opinions about noise from the perspective of their daily lives. Second, the blind older adults evaluated the current situation of the acoustic environment in the nursing home from the perspective of the residential environment and suggest the improvement. Finally, the sound perception experience of the blind older adults was reflected on the dimension of sound cognition, combining the sound context with the residents' experience. The blind older adults, therefore, need sound sources to meet their requirements, and avoid the interference caused by other sound sources. The sound requirements of the blind older adults need to be fulfilled, especially the need for the setting of the informational sound source. In addition, soundscape memory, as part of the interpretation of auditory sensation, was found affect the sound cognition of blind older adults along with the sound context.

This study shows that older adults having aural- diversity experience and auditory impairments/hearing loss affected their perception of the acoustic environment, and confirms that the visual impairment brought about the differences in sound perception and was related to the differences in the daily behavioral activity and sound requirements of the blind older adults. Since sound is a necessary element for them to perceive direction, activity and other people, silence is not necessary for them during the daytime. Therefore, the aural diversity of the older adults places a higher demand on designers and institution managers for inclusion and refinement to better serve the needs of blind older adults with different visual impairments.

**Author Contributions:** Conceptualization, Y.W., J.M. and J.K.; methodology, Y.W. and J.K.; software, S.H.; validation, Y.W. and J.M.; investigation, S.H. and Y.W.; data curation, S.H.; writing—original draft preparation, S.H.; writing—review and editing, Y.W. and S.H.; supervision, J.K.; funding acquisition, J.M. and J.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the Youth Program of National Natural Science Foundation of China (grant number: 52208017), and Ministry of Science and Technology of China (grant number: G2021179030L).

**Institutional Review Board Statement:** The study was conducted in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of School of Architecture, Harbin Institute of Technology.

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** The original data from the study are included in the text and Appendix A; further inquiries can be directed to the respective author.

**Acknowledgments:** We thank the blind older adults who participated in this study, the staff who helped us survey the nursing home and reach out to participants, and the Harbin Institute of Technology's Visually Impaired Aging Test Team for their contributions to data collection.

**Conflicts of Interest:** The authors declare no conflict of interest.
