A city's soundscape or the auditory component of its landscape is vital to its experience, yet urban design is primarily concerned with the visio-spatial experience. To enhance the quality of the urban environment, the focus of the existing noise management approach on merely reducing 'noise' or undesirable sounds is insufficient.
Soundscape as a resource and heritage
Sound is an existential necessity with ecological and social value. Natural soundscapes are beneficial to human health, and cultural soundscapes are an important part of a city's heritage. Noise can be utilized as a resource to structure the categorical space of noises in a city to enhance the quality of its urban environment. It is possible to mask undesirable anthrophonies or human-generated mechanical sounds by using geophonies such as wind and water flow, as well as biophonies produced by living beings.
The changing soundscape of a city provides insight into its life and culture both spatially and temporally. In a multi-sensorial and complex urban setting, diverse sense modalities interact with our auditory judgments to determine how we perceive and experience the sonic environment, both individually and collectively.
Employing auditory-visual stimulants to enhance urban design
A city's soundscape can be improved by preserving its distinct sound pattern, which gives it character and makes life more meaningful for its human and non-human populations. Different sources of sound command varying degrees of attention depending on their intensity as well as their significance and relevance to the listener. The congruence of a soundscape, or how the sounds blend in with the urban surroundings, also influences perception.
To give individual and societal meaning to the impact of sound on city dwellers, a comprehensive evaluation must include psychological, physiological, and sociological aspects in addition to physical factors. Accounting for people's subjective perceptions of urban noise can help us see noise in a more positive light.
Urban morphologies generate distinct urban soundscapes. Soundscape planning requires shaping territories based on sound signals by creating less homogeneous acoustic environments with the goal of masking undesirable sounds with desirable sounds.
A soundscape approach to urban design involves establishing spaces that amplify desirable sounds like flowing water while eliminating or reducing undesirable sounds such as traffic. Design elements such as vegetation and other noise barriers, as well as topography designs can be used to mitigate undesirable noise in a city's soundscape.
Achieving a balance between audio-visual congruency and attention focusing
Source visibility and noise perception are influenced by audio-visual congruency and attention focusing. Adding a visual stimulus on top of an auditory stimulus may cause the noise source to receive more attention. When sound pressure levels are low, it is best to conceal the source, to avoid drawing attention to it. Natural sounds like bird calls or leaf rustling divert the listener's attention away from unpleasant sound sources when they are obscured by vegetation. Some bird sounds have been linked to feelings of relief from cognitive fatigue. Neighbourhood green that is not directly visible is also beneficial, albeit with a smaller impact on noise perception. Individual variances in noise sensitivity and environmental preference, however, influence psychological restorative outcomes.
Reduced visibility may be accompanied by a reduction in apparent loudness as long as the source is visible. When the source is completely obscured from view, the effect is reversed. Throughout evolution, the sense of hearing has evolved for detecting and reacting to danger. If a reasonably loud noise event is not accompanied by a corresponding visual stimulus, it may be perceived as an ambiguous threat. Visual screening without adequate noise reduction contradicts expectations, and the loudness may be overestimated due to audio-visual incongruency. As a result, areas with higher levels of sound pressure require audio-visual coherence rather than congruence. In urban environments, fences and vegetation that provide partial visibility can help maintain the balance of focus and audio-visual congruence.
Fine-tuning an ambient soundscape
The landscape components of an urban soundscape must be carefully selected to optimize the psycho-social experience. An ideal soundscape configuration supports vital natural acoustic phenomena such as bird calls while also facilitating important economic and social activities such as street trading. If tranquillity is the priority, ambient noise must be controlled through vegetative and non-vegetative sound barriers. If the goal is to maintain the vibrancy of the soundscape, the focus must be on landscape ecology in order to improve biodiversity and the integrity of water features. To preserve sonic representativeness, the 'sound mark,' or the most representative sound of a specific place or time, must be treated as cultural heritage, and its location of propagation must be preserved.
A well-designed sonic environment can stimulate psychological restoration and improve physiological well-being, positively impacting urban public health. It can promote social engagement, increase subjective safety, and create sound signatures for cities. This would only be possible with increased cooperation between experts in the environmental and social sciences, urban planners, and citizens—the creators of urban sounds.
(Ann Rochyne Thomas is a bio-climatic spatial planner and founder of the Centre for Climate Resilience - a sustainability and climate change advisory.)
