**3. Perception of soundscapes**

Sound, as a landscape element, has not received much interest in landscape design and planning compared to vision. Listening to an environment is generally not the primary activity or interest of a person (Jennings & Cain, 2012); however information provided by the visual landscape play a great role in realizing our daily activities. The concept of soundscape has recently gained attention of planning and design disciplines where focus is generally on the visual aspect, rather than the acoustic. One of the reasons might be that most of the time designers' and planners' lack of scientific knowledge on acoustics. Concepts like "weighted sound levels", "absorption coefficient", and logarithmic measurements may seem unfamiliar and intimidating. Although noise mapping is quite a popular tool in environmental assessment studies, sound is rarely considered as a design element in landscape. Sound does not literally mean "noise". While some sounds can be disturbing, some sounds can give pleasure to an individual. However, sound as a sensory experience is rather different from vision. Acoustic space does not have obvious boundaries and is less precise in terms of orientation and localization (Porteous, 1996). Therefore assessment of sound as a design element is much complex than the visual dimension. Sound is an important element of a place which affects individual's perception and understanding of an environment. People derive information from sounds, just like visual environment. Sound can act as a guide for way finding or a cautionary signal for alert. In the context of space, soundscape can be defined as the acoustic character of an environment.

Urban environments are diverse and complex acoustic environments. They include different kinds of sound resources. Therefore, outdoor acoustic environment studies are mostly concerned with urban soundscapes. Evaluation of urban soundscapes is crucial not only for noise mitigation but also to assessment of acoustic comfort which is integral to overall environmental quality.

The term of soundscape was first coined by R. Murray Schafer. In his book "The Tuning of the World" (1977), he describes the soundscape as any acoustic field of the study; it may be a musical composition or a radio program or an acoustic environment. Influenced by Gestalt figure-background relationship (see section 2.2.6), Schafer identified three elements of a soundscape; (i) keynote sounds, (ii) sound signals, and (iii) soundmarks. Keynote sounds are background sounds and can be perceived subconsciously. Schafer suggests keynote sounds might have an effect on our behavior and moods since they are permanently there, whether we hear them consciously or not. Traffic sound is often given as a keynote example for contemporary urban environments. Sound signals, are foreground sounds and are listened to consciously (e.g. sirens). Finally, soundmarks (derived from landmark) are unique to that environment or to people in the community, thus they need to be protected. These elements have established a foundation for many soundscape studies so far.

The most noticeable study on the relationship between landscape architecture and soundscape is Hedfors's (2008) book "Site Soundscapes: landscape architecture in the light of sound". In his book, he analyzes sound in context of landscape architecture. He suggests a hypothetical model, named "the model of prominence" as a starting point for

provide landscape architects to improve their place-making strategies in terms of design and

Sound, as a landscape element, has not received much interest in landscape design and planning compared to vision. Listening to an environment is generally not the primary activity or interest of a person (Jennings & Cain, 2012); however information provided by the visual landscape play a great role in realizing our daily activities. The concept of soundscape has recently gained attention of planning and design disciplines where focus is generally on the visual aspect, rather than the acoustic. One of the reasons might be that most of the time designers' and planners' lack of scientific knowledge on acoustics. Concepts like "weighted sound levels", "absorption coefficient", and logarithmic measurements may seem unfamiliar and intimidating. Although noise mapping is quite a popular tool in environmental assessment studies, sound is rarely considered as a design element in landscape. Sound does not literally mean "noise". While some sounds can be disturbing, some sounds can give pleasure to an individual. However, sound as a sensory experience is rather different from vision. Acoustic space does not have obvious boundaries and is less precise in terms of orientation and localization (Porteous, 1996). Therefore assessment of sound as a design element is much complex than the visual dimension. Sound is an important element of a place which affects individual's perception and understanding of an environment. People derive information from sounds, just like visual environment. Sound can act as a guide for way finding or a cautionary signal for alert. In the context of

space, soundscape can be defined as the acoustic character of an environment.

Urban environments are diverse and complex acoustic environments. They include different kinds of sound resources. Therefore, outdoor acoustic environment studies are mostly concerned with urban soundscapes. Evaluation of urban soundscapes is crucial not only for noise mitigation but also to assessment of acoustic comfort which is integral to overall

The term of soundscape was first coined by R. Murray Schafer. In his book "The Tuning of the World" (1977), he describes the soundscape as any acoustic field of the study; it may be a musical composition or a radio program or an acoustic environment. Influenced by Gestalt figure-background relationship (see section 2.2.6), Schafer identified three elements of a soundscape; (i) keynote sounds, (ii) sound signals, and (iii) soundmarks. Keynote sounds are background sounds and can be perceived subconsciously. Schafer suggests keynote sounds might have an effect on our behavior and moods since they are permanently there, whether we hear them consciously or not. Traffic sound is often given as a keynote example for contemporary urban environments. Sound signals, are foreground sounds and are listened to consciously (e.g. sirens). Finally, soundmarks (derived from landmark) are unique to that environment or to people in the community, thus they need to be protected.

These elements have established a foundation for many soundscape studies so far.

The most noticeable study on the relationship between landscape architecture and soundscape is Hedfors's (2008) book "Site Soundscapes: landscape architecture in the light of sound". In his book, he analyzes sound in context of landscape architecture. He suggests a hypothetical model, named "the model of prominence" as a starting point for

planning.

**3. Perception of soundscapes** 

environmental quality.

landscape architects. The model is also grounded on Gestalt figure-background relationship, like Schafer's work. It is based on description of the sounds. In Hedford's model figure-ground relationship is combined with two other dimensions; intensity and clarity (Figure 6). According to Hedford, a soundscape can be described as clear if prominent sounds are strongly experienced against a weak background. However, if prominent sounds are weaker than the background, then the soundscape becomes crowded. If both prominent sounds and the background are experienced equally strong, the soundscape can be described as powerful. On the contrary, if both are experienced weak, the soundscape becomes mild.

Fig. 6. The model of prominence (Hedfords, 2008).

Similar to natural landscapes, natural sounds such as bird sound and water sound are highly preferred by people. This may be explained through evolutionary perspective on landscape perception as well as therapeutic effects of natural landscapes (please refer to section 2.4). In fact, relaxation is found to be an important factor for urban open soundscapes (Yang & Kang, 2005). It is known that natural sounds such as bird and water sound can help people feel relaxed (Carles *et al.*, 1999).

Landscape Perception 269

Fig. 7. Soundscape design strategies (Zhang & Kang, 2007).

Besides sound level measurements, perceived acoustic quality and preferences are often evaluated through interviews, questionnaires and soundwalks. During sound level measurements A-weighted equivalent continuous sound level (LAeq) is measured and statistical sound levels (Leq90, Leq50, and Leq10) are calculated. Equivalent continuous sound level presents the average level of noise over a time period, while statistical sound levels are used to define maximum, intrusive, median and background sound levels (Kang, 2007). Identification of the sounds which are perceived by the user is generally the first step of soundscape preference research. This procedure provides researchers an insight to perceived foreground sounds, background sounds and soundmarks. Rating scales are frequently employed in preference research. Participants are asked to rate the acoustic environment or a particular sound. The rating scale generally involves bipolar verbal descriptions such as like-dislike, noisy-quite, favorite-unfavorite etc. Semantic differential analysis is another tool which is commonly used to investigate people's emotional responses

*Research methodology* 

Since sound perception is assumed to be a personal and therefore unique phenomenon, most researchers believe that perception of the acoustic environment is affected by personal factors such as demographics and culture. Yu & Kang (2010) found that people preferred natural sounds with increasing age and education level. Their results showed no significant correlation between preferences and occupation, and residence status. They found that gender influenced preference only for some sound types (e.g. bird sound).

Anderson *et al.* (1983) emphasize the importance of expectations in people's sound evaluations (Hedfords, 2008). People might tolerate or appreciate undesirable sounds if they expect to hear them in an environment. For instance some traffic sounds were found to be appreciated in urban environments. Thus, cultural and life-style differences might play role in evaluations of environments with different sound levels.

Sound types have also been found to be related to acoustic comfort evaluations; pleasant sounds, with either high or low sound levels, are perceived to improve the acoustic comfort (Yang & Kang, 2005). The source of the sound type can also affect preference. Zhang & Kang (2007) found that while "music on the street" was rated as favorite by 46% of the participants, 15% rated for music from stores, and only 2% rated for music from cars. Perception of the soundscape is also influenced by the activity involved and hence listening situation (Jennings & Cain, 2012).

Although sound level measurements (e.g. A-weighted levels) are widely used in soundscape research, it is also indicated that perception of the acoustic environment is independent from sound levels (Jennings & Cain, 2012; Szeremeta & Zanin, 2009). Reducing sound levels do not always improve perceived quality of acoustic environment (Yang & Kang, 2005). Furthermore, elimination of negative sounds from the environment does not necessarily make the acoustic environment more positive, may even generate anxiety (Cain *et al.*, 2011). However, Yang & Kang (2005) have found that background sound level is an important factor in evaluating soundscape in urban open public spaces; they suggest that reduced background sound level can help to create comfortable acoustic environments.

Visual perception also affects sound perception; Faburel & Gourlot (2009) found that visual images can reduce the negative effect of a sound, equivalent of up to 10dB decrease in the sound pressure level (SPL) (Solène, M., 2011). Yang and Kang (2005) also concluded that visual factors affect acoustic comfort evaluations and they suggested that interaction of visual and auditory perception work together "*as an aesthetic comfort factor"*. Carles *et al.*'s (1999) study supports this idea. They presented varying combinations of visual and auditory stimuli and participants were asked to rate each image, each sound, and finally each combination. It is found that sounds in the scenes containing vegetation or abundant water were rated higher; hence they concluded that visual and acoustic information can reinforce or interfere with each other. Furthermore, people are less annoyed by the sounds when the source is not visible (Solène, M., 2011). Zhang & Kang (2007) proposed some suggestions for creation of soundscapes in urban environments. They state that if SPL is higher than 65-70 dBA, then people will feel annoyed. Figure 7 shows their design suggestions.

Since sound perception is assumed to be a personal and therefore unique phenomenon, most researchers believe that perception of the acoustic environment is affected by personal factors such as demographics and culture. Yu & Kang (2010) found that people preferred natural sounds with increasing age and education level. Their results showed no significant correlation between preferences and occupation, and residence status. They found that gender influenced preference only for some sound types (e.g. bird

Anderson *et al.* (1983) emphasize the importance of expectations in people's sound evaluations (Hedfords, 2008). People might tolerate or appreciate undesirable sounds if they expect to hear them in an environment. For instance some traffic sounds were found to be appreciated in urban environments. Thus, cultural and life-style differences might play role

Sound types have also been found to be related to acoustic comfort evaluations; pleasant sounds, with either high or low sound levels, are perceived to improve the acoustic comfort (Yang & Kang, 2005). The source of the sound type can also affect preference. Zhang & Kang (2007) found that while "music on the street" was rated as favorite by 46% of the participants, 15% rated for music from stores, and only 2% rated for music from cars. Perception of the soundscape is also influenced by the activity involved and hence listening

Although sound level measurements (e.g. A-weighted levels) are widely used in soundscape research, it is also indicated that perception of the acoustic environment is independent from sound levels (Jennings & Cain, 2012; Szeremeta & Zanin, 2009). Reducing sound levels do not always improve perceived quality of acoustic environment (Yang & Kang, 2005). Furthermore, elimination of negative sounds from the environment does not necessarily make the acoustic environment more positive, may even generate anxiety (Cain *et al.*, 2011). However, Yang & Kang (2005) have found that background sound level is an important factor in evaluating soundscape in urban open public spaces; they suggest that reduced background sound level can help to create comfortable acoustic

Visual perception also affects sound perception; Faburel & Gourlot (2009) found that visual images can reduce the negative effect of a sound, equivalent of up to 10dB decrease in the sound pressure level (SPL) (Solène, M., 2011). Yang and Kang (2005) also concluded that visual factors affect acoustic comfort evaluations and they suggested that interaction of visual and auditory perception work together "*as an aesthetic comfort factor"*. Carles *et al.*'s (1999) study supports this idea. They presented varying combinations of visual and auditory stimuli and participants were asked to rate each image, each sound, and finally each combination. It is found that sounds in the scenes containing vegetation or abundant water were rated higher; hence they concluded that visual and acoustic information can reinforce or interfere with each other. Furthermore, people are less annoyed by the sounds when the source is not visible (Solène, M., 2011). Zhang & Kang (2007) proposed some suggestions for creation of soundscapes in urban environments. They state that if SPL is higher than 65-70 dBA, then people will feel annoyed. Figure 7 shows their design

in evaluations of environments with different sound levels.

situation (Jennings & Cain, 2012).

environments.

suggestions.

sound).

Fig. 7. Soundscape design strategies (Zhang & Kang, 2007).

#### *Research methodology*

Besides sound level measurements, perceived acoustic quality and preferences are often evaluated through interviews, questionnaires and soundwalks. During sound level measurements A-weighted equivalent continuous sound level (LAeq) is measured and statistical sound levels (Leq90, Leq50, and Leq10) are calculated. Equivalent continuous sound level presents the average level of noise over a time period, while statistical sound levels are used to define maximum, intrusive, median and background sound levels (Kang, 2007). Identification of the sounds which are perceived by the user is generally the first step of soundscape preference research. This procedure provides researchers an insight to perceived foreground sounds, background sounds and soundmarks. Rating scales are frequently employed in preference research. Participants are asked to rate the acoustic environment or a particular sound. The rating scale generally involves bipolar verbal descriptions such as like-dislike, noisy-quite, favorite-unfavorite etc. Semantic differential analysis is another tool which is commonly used to investigate people's emotional responses

Landscape Perception 271

authors suggest that culturally significant sounds or sonic art could be introduced to give a unique character and to increase excitement or attractive quality. The authors state that Kano model is successfully used in automobile industry for sound quality assessments. However, this model might seem confusing for spatial designers and planners .The authors also emphasize the need for application of the framework through real-life examples. Please

Solène (2011) applied cognitive mapping technique in her study on urban soundscapes. Participants were asked to draw graphical representations of sonic ambiences of three urban squares. They were also asked to describe their preference for ideal sonic environments in squares. Boundary was found to be an essential element in perceived ideal sonic environments since most participants described closed or semi-open squares. On the contrary, open squares were associated with negative sonic ambiance. Depending on the results, the author inferred that there is a strong bond between urban typology and perceived sonic ambiance. She concluded that sonic mind maps were appropriate for

Despite the short history of soundscape research on outdoor environments, there seems to be a variety of research techniques and methodologies which can be adapted to the researcher's objectives. Still, many issues such as interrelationships between factors that affect soundscape preferences and the effects of spatial design on acoustic comfort need to be further investigated. Spatial designers and planners can contribute to the soundscape research by developing new models and methodologies in order to display and emphasize

Our landscapes are natural and cultural heritage of our societies. With the rapid urbanization and development processes, change has become an inevitable outcome for our landscapes in global scale. Unfortunately, landscape change often occurs in negative ways. Loss of diversity and identity should be the main concern for future design and planning research for landscape architects. However, the role of perception and its effects on spatial

If landscape architecture aims to create livable and effective environments for people in the community, people's perception and interpretation of environments must be investigated. One can argue that landscape assessments should be made by experts because of their knowledge and experiences and general public can't judge environmental quality. On the other hand, environmental quality issues are still on the agenda. To some extent, local, national and even international authorities can be blamed for ignoring knowledge and suggestions of environmental designers and planners in sustainable development. Certainly, professionals have a lot to offer in terms of knowledge and skills. However, knowing and understanding the basic relationships between people and their environments is a necessity. This chapter has summarized basic information and approaches on landscape perception both in visual and auditory context, aiming to provide an insight on perceptual and cognitive dimensions of environmental research. However, there are more to landscape perception research. Reference list can provide readers with valuable resources to read.

see the reference for further details of the framework.

studying psychoacoustics of an urban environment.

their role on creating livable and high quality environments.

behavior and attitudes must be realized first.

**4. Conclusion** 

towards sound types and acoustic environments. These techniques can easily be applied any time to anyone without a hearing deficit or disorder. However, the soundwalk technique depends on more conscious listening state. During soundwalks, participants observe and listen to their environments very carefully while walking along a path and make judgments on the acoustic environment.

Previous studies have been carried out either in laboratories or in-situ. Binaural recordings are preferred for laboratory studies. Laboratory conditions are also suitable for assessment of the interaction between visual and auditory stimuli with different characteristics. However, if the soundscape of a particular place is to be assessed, considering primarily that visual perception affects perception of acoustic environment. it is best to carry out the study in-situ. Furthermore, for researchers from design and planning disciplines it might be difficult to establish and maintain laboratory conditions for acoustic evaluations due to lack of technical and scientific knowledge. Therefore, a multidisciplinary approach might be helpful in designing and conducting more effective research on soundscapes.

Zhang & Kang (2007) proposed a detailed system for investigation of urban open space soundscapes. They identified four facets; (i)characteristics of each sound, (ii)acoustic effects of the space, (iii)characteristics of users and (iv)other aspects of physical and environmental conditions. Description of each facet is summarized below.

Sound: For each sound, it is recommended that both steady state and the statistical SPL, spectrum, temporal conditions, source location, source movement and the psychological and social characteristics should be taken into account. Temporal conditions include variation (hour, day, season), duration and impulsive characteristics. Meaning, natural or artificial sounds, relation to activities, soundmarks and listening state (descriptive or holistic) should be considered in context of psychological and social characteristics.

Space: The shape of the space, boundary materials, street and square furniture, landscape elements, reverberation, reflection pattern and/or echogram, general background sound and sounds around the space are the characteristics to be considered related to the space.

People: Social, demographic, cultural characteristics of users and acoustic condition at users' home, work etc. should be assessed.

Environment: Microclimate conditions, lighting, visual, landscape and architectural characteristics are among the environmental characteristics that need to be taken into consideration.

Jennings & Cain (2012) propose a framework which uses Kano model in order to provide designers and planners a tool for predicting impacts of design interventions on soundscape. Kano model is generally used in product development for determination of customer needs and satisfaction. Jennings & Cain (2012) suggest that Kano model can help to clarify thinking, since perception of the soundscapes is a complex process. To summarize their proposal, there are three attributes to be assessed in Kano model; basic requirements, performance requirements and excitement (or attractive) requirements. The first step is to satisfy basic requirements, such as fulfilling legislative requirements for noise control. Then performance requirements need to be assessed in order to find out user needs and expectations. Use of emotional perceptual dimensions, interactive simulations and soundwalks might be helpful in this step. Finally for the excitement requirements, the

towards sound types and acoustic environments. These techniques can easily be applied any time to anyone without a hearing deficit or disorder. However, the soundwalk technique depends on more conscious listening state. During soundwalks, participants observe and listen to their environments very carefully while walking along a path and make judgments

Previous studies have been carried out either in laboratories or in-situ. Binaural recordings are preferred for laboratory studies. Laboratory conditions are also suitable for assessment of the interaction between visual and auditory stimuli with different characteristics. However, if the soundscape of a particular place is to be assessed, considering primarily that visual perception affects perception of acoustic environment. it is best to carry out the study in-situ. Furthermore, for researchers from design and planning disciplines it might be difficult to establish and maintain laboratory conditions for acoustic evaluations due to lack of technical and scientific knowledge. Therefore, a multidisciplinary approach might be

Zhang & Kang (2007) proposed a detailed system for investigation of urban open space soundscapes. They identified four facets; (i)characteristics of each sound, (ii)acoustic effects of the space, (iii)characteristics of users and (iv)other aspects of physical and environmental

Sound: For each sound, it is recommended that both steady state and the statistical SPL, spectrum, temporal conditions, source location, source movement and the psychological and social characteristics should be taken into account. Temporal conditions include variation (hour, day, season), duration and impulsive characteristics. Meaning, natural or artificial sounds, relation to activities, soundmarks and listening state (descriptive or

Space: The shape of the space, boundary materials, street and square furniture, landscape elements, reverberation, reflection pattern and/or echogram, general background sound and sounds around the space are the characteristics to be considered related to the space.

People: Social, demographic, cultural characteristics of users and acoustic condition at users'

Environment: Microclimate conditions, lighting, visual, landscape and architectural characteristics are among the environmental characteristics that need to be taken into

Jennings & Cain (2012) propose a framework which uses Kano model in order to provide designers and planners a tool for predicting impacts of design interventions on soundscape. Kano model is generally used in product development for determination of customer needs and satisfaction. Jennings & Cain (2012) suggest that Kano model can help to clarify thinking, since perception of the soundscapes is a complex process. To summarize their proposal, there are three attributes to be assessed in Kano model; basic requirements, performance requirements and excitement (or attractive) requirements. The first step is to satisfy basic requirements, such as fulfilling legislative requirements for noise control. Then performance requirements need to be assessed in order to find out user needs and expectations. Use of emotional perceptual dimensions, interactive simulations and soundwalks might be helpful in this step. Finally for the excitement requirements, the

holistic) should be considered in context of psychological and social characteristics.

helpful in designing and conducting more effective research on soundscapes.

conditions. Description of each facet is summarized below.

home, work etc. should be assessed.

consideration.

on the acoustic environment.

authors suggest that culturally significant sounds or sonic art could be introduced to give a unique character and to increase excitement or attractive quality. The authors state that Kano model is successfully used in automobile industry for sound quality assessments. However, this model might seem confusing for spatial designers and planners .The authors also emphasize the need for application of the framework through real-life examples. Please see the reference for further details of the framework.

Solène (2011) applied cognitive mapping technique in her study on urban soundscapes. Participants were asked to draw graphical representations of sonic ambiences of three urban squares. They were also asked to describe their preference for ideal sonic environments in squares. Boundary was found to be an essential element in perceived ideal sonic environments since most participants described closed or semi-open squares. On the contrary, open squares were associated with negative sonic ambiance. Depending on the results, the author inferred that there is a strong bond between urban typology and perceived sonic ambiance. She concluded that sonic mind maps were appropriate for studying psychoacoustics of an urban environment.

Despite the short history of soundscape research on outdoor environments, there seems to be a variety of research techniques and methodologies which can be adapted to the researcher's objectives. Still, many issues such as interrelationships between factors that affect soundscape preferences and the effects of spatial design on acoustic comfort need to be further investigated. Spatial designers and planners can contribute to the soundscape research by developing new models and methodologies in order to display and emphasize their role on creating livable and high quality environments.
