Planning Strategies and Design Concepts
Strategies for Acoustical Resilience towards Liveable and Sustainable Urban Neighborhoods
A Case Study of Bangalore City, India
2024 年 12 巻 3 号 p. 16-35
詳細
2024 年 12 巻 3 号 p. 16-35
This research explores the concept of sound as a determinant for planning and designing liveable neighborhoods based on an understanding of noise pollution. The paper broadly begins with an interest in sustainable designs of urban residential neighborhoods globally and specifically in typical cities of India and the Asian subcontinent. The UN SDG 11 mentions, 'make cities & human settlements inclusive, safe, resilient, and sustainable.' While the most evident sustainability parameters are known, one of the commonly understated criteria is noise pollution. Hearing is one of the five fundamental senses; hence, safer sound levels should be one of the primary factors in designing healthy cities. Literature understandings are derived from soundscape theories of Schafer & Truax, who extended the concept of acoustics from architecture to an urban scale; inferences are drawn from legislations and co-related with current scenarios investigated by way of primary surveys in the fast-growing city of Bangalore, India. The study proposes a methodological triangulation with three aspects of primary data collection: field surveys for street-level acoustics (using sound meters/smartphone Apps), Interview surveys (in-person), and Questionnaire surveys (online). Results revealed a sharp difference between the norms' acoustical thresholds and the audited survey scores. Upon analytical deductions, the study concludes with a strategic framework for an integrated approach to achieve ‘urban acoustical resilience’ that responds to spatial patterns. This framework suggests strategies under two broad aspects of design guidelines and a regulatory mechanism to achieve globally acoustical-compliant sustainable neighborhoods.
Rapid urbanization has led to unintended by-products and public health challenges, including air, water, soil, and noise pollution. While related concerns such as biodiversity loss, global warming, waste management, and such issues are well-documented, noise pollution remains an ignored environmental threat that significantly impacts city dwellers (UNEP, 2022). It is so omnipresent in today's urban areas that it often fails to be noticed as a critical parameter of a healthy, sustainable society. The World Health Organization acknowledges that noise is a significant public health issue in cities that continues to grow (World Health Organization, 2018).
Primarily, city designs are based on tangible aspects of transportation, land uses, amenities, water, and landforms. Meanwhile, sound levels rarely contribute to decision-making in the master planning processes. Heilig (1992) ranked the order in which he believed the various senses capture our attention: vision- 70%; audition- 20%; olfaction- 5%; touch- 4%; taste- 1% (Spence, 2020). However, does this sensorial hierarchy apply to our appreciation of urbanscape experiences and the role of hearing cognition? While architectural acoustics is a well-defined science of building designs for indoor comfort conditions, urban-level acoustical designs have yet to be a formalized stream. Much is unexplored in the field. The New Urban Agenda attributes one of the parameters for the resilience of cities to reducing noise and promoting attractive and liveable cities (U.N. Habitat, 2020). Generally, urban planning and design envision creating liveable cities that rely on the visual aesthetic qualities of the physical environment (Urban Design Lab, 2023) and not so much on the sonic qualities of the urban spaces. Hence, the study aims to perceive the trans-disciplinary understanding of urban design and urban acoustics in neighborhoods using mixed-method research of qualitative perceptions and quantitative evaluation. The study is conducted in Bangalore (Bengaluru), on the southern peninsula of India, in the Asian sub-continent. It is the capital city of Karnataka state and a fast-urbanizing cosmopolitan city on the global map (B.PAC, 2023). The study thus instigates insight into this critical yet unexplored premise in similar fast-developing towns in Asia, the global south, and beyond.
Liveability commonly refers to the degree to which a place is good for living. It denotes the fit of institutional arrangements with human needs and capacities that explains observed differences in happiness regarding need-environment fit (Veenhoven, 2014). “U.N. definition quotes that liveability is determined by human factors such as health, security….”(Amir, Sadoway et al., 2023). “The New Urban Agenda highlights linkages between sustainable urbanization and……(also) improved quality of life, and it insists on the incorporation of all these sectors in every urban development or renewal policy and strategy" (U.N. Habitat, 2020). It commits to "improving the resilience of cities to…. improving physical and mental health, and household…..., (as well) to reducing noise and promoting attractive and liveable cities, human settlements, and urban landscapes” (U.N. Habitat, 2020). Thus, one of the attributes of liveability is 'noise' contributing to the general health of urban dwellers, and liveability, in turn, becomes a factor in urban development. To perceive the impact of soundscapes in terms of acoustic comforts to urban residents, the main objectives of the study are:
The impending query thus- Does 'sound' as a parameter insinuate planning and design decisions for creating livable urban neighborhoods in cities? Hypothesizing the inquiry- 'Street-level acoustics become a function of the spatial pattern of the neighborhood and determinant of the liveability.' This inquiry is enabled with a methodology that involves two dimensions of comparative analysis- spatial planning of neighborhoods and observations of prevalent acoustical conditions.
The paper runs in four sections, with the first part presenting a literature review on urban acoustics, soundscape theories, sound mapping techniques, and tools. The second part describes the research design and methodology for discussing the developed soundscape audit surveys. This methodology leads to a quantitative assessment and a co-relative analysis with India's existing regulatory framework for noise control. The third section presents the results of the primary surveys and discussions, deriving a qualitative understanding based on questionnaires and interviews. The final section concludes with a proposed strategic framework to achieve 'urban acoustical resilience' in neighborhoods.
Why is urban acoustics relevant in cityscapes? Architectural acoustics for building interiors has been an essential aspect of deliberation and innovation in infrastructure designs, materials, techniques, or engineering to achieve user comfort. Similarly, outdoor spaces in people's neighborhoods have become crucial to be designed with ideal soundscapes. Outdoor experiences required for overall healthy well-being (Frysh, 2023) should be laden with safer sound exposures indoors and outdoors, which are impacted by the exact noise source. A study explored the potential of traditional outdoor spaces for the sustainable development of urban housing in Iraq, focusing on socio-environmental values wherein acoustic privacy from the surroundings was an essential criterion of satisfaction amongst residents (Itma and Khaleefa, 2024). Hence, urban acoustics is a crucial parameter for liveable spaces and has been gaining scientific momentum, reflected in the exponential increase in the number of international publications on the subject since 2016 compared to 2000 (Luzzi, Busa et al., 2018). Results from research on the liveability of neighborhoods for elderly citizens in Bangalore City revealed that 75% of elderly respondents expressed concern about neighborhood public spaces being cluttered, noisy, and unsafe (Patil and Raj, 2019).
Issues concerning noise pollutionThere are several impending issues, especially man-made noises, which are the leading cause of noise pollution, altering the acoustical environment in cities and impacting humans, birds, animals, and aquatic habitats alike (Prana Air, 2023). Especially motors are a leading cause of noise pollution, with car horns running at 90 dB and bus horns at 100 dB, according to a recent survey in Jan 2023 across 15 Indian cities (Earth5r, 2023). Noise pollution impacts two broader aspects- the general health of individuals and the quality of urban life (EEA, 2020). This severity of health effects due to noise against the number of people affected is described explicitly by WHO (Figure 1).
WHO stipulates sound levels less than 70 dB as acceptable, beyond which hearing impairment sets in for an exposure period of 24 hours (World Health Organization, 2011). The range of human hearing is operated through a relatively fixed frequency band between 20 Hz and 20 KHz (Fowler, 2017). Anything beyond this and more than 8 hours of exposure to levels between 80 to 85 dB proves hazardous to health. World Health Organization (2010) for community noise recommend less than 30 A-weighted decibels (dB[A]) for sleep of good quality and less than 35 dB(A) in classrooms to allow good teaching and learning conditions. The empirical findings in a study conducted in Dhaka (Sultana, Suhi et al., 2022) towards assessing factors affecting the urban quality of life or liveability under two aspects of environmental and social issues showed that 77.8% of residents expressed dissatisfaction about sound pollution second to air quality at 92.5% respondents followed by cleanliness, water quality, and odor pollution.
The universal aspect regarding the prevalence and adversities of noise pollution are uniformly witnessed in different studies conducted across the world in cities such as Denmark (Sørensen, Hvidberg et al., 2011), European cities (Harvey, 2019), Brazil (Barbosa and Cardoso, 2005), Bangladesh (Chakraborty, Khan et al., 2005), Malaysia (Thomas, Mariah et al., 2007), China (Wang, Wang et al., 2022), and India (Jamir, Nongkynrih et al., 2014). The degree of impact may vary based on geographical locations, urban population, density, and the degree of subjectivity that noise pollution projects to a certain extent. However, the concerns are noted worldwide, and the magnitude of concern is alarming as well. Research conducted by the United Nations Environment Programme (Hindustan Times, 2022) on global noise pollution scenarios reveals that Asian cities account for 10 out of 15 most noise-polluted towns in the world, with the top 3 being South Asian cities; the list includes New York, Nigeria, and Manila as well. Hence, addressing the issue has become a global social and environmental cause impacting liveability standards.
Soundscape theories and sound mapping techniquesThe term 'soundscape' was first noticed in 1969 by Michael Southworth, a PhD scholar at M.I.T., Boston, in his article based on his Master's Thesis in city planning completed in 1967 (Southworth, 1969). In the 1970s, the theory became associated with Raymond Murray Schafer, a Canadian composer and educator (Axelsson, Guastavino et al., 2019) who defined it as the "study of effects of the acoustic environment or soundscape on the physical responses or behavioral characteristics of creatures living within it" (Schafer, 2017). Soundscape may be subjective, defined as a totality of the sound environment "with emphasis on the way it is perceived and understood by the individual, or by a society" (Truax and World Soundscape Project, 1978). Schafer opinionated that just as vision can reveal a place's physical identity, so does the sense of hearing create an image or perception of a place. He gives two typologies of soundscapes: hi-fi (sounds of nature, high quality with cyclic and original sonorities) and lo-fi (sounds of an industrial city with repetitive and monotonous sonorities). Thus, Schafer and Truax extended the acoustics concept to the urban realms.
These soundscapes are not singular to assess but involve a holistic, multisensory perspective to perceive outcomes that extend beyond auditory judgments (Axelsson, Guastavino et al., 2019). Technical assessment is one aspect of sound mapping; the other is a qualitative assessment of urban sounds. Literature from the last decade was sieved through and shortlisted based on closely related aspects of urban noise, urban scale, and assessment methodologies. Most studies adopted sound level meters and relied on evaluations with suitable measurement methods involving a particular neighborhood profile, focus user group, or specific intent of the inquiry. The concept of 'Soundwalk' was introduced by members of the World Soundscape Project under Schafer in Vancouver in the 1970s, which simply means to walk with a focus on listening to the environment closely and analytically (Westerkamp, 1974). This concept is partially adopted in the audit system in this study.
Another study reported a co-constructed experiment between researchers and local authorities in Rezé, France, on urban noise diagnosis using a smartphone application called NoiseCapture (Can, Audubert et al., 2023). It proposed a citizen-led structure for decisions on noise management. Soundscape recognition models were used in outdoor environmental acoustic assessment by clustering people based on differences in sound source perceptions (Jo and Jeon, 2021). There were three clusters with three levels of attentiveness to the sound source, such as attentiveness to traffic noise or human sounds. Each cluster derived soundscape perceptual components differently and aided in apt design decisions.
In terms of measuring equipment, the objective of this study is to adopt an easy-to-use handheld tool to assess urban sound levels during surveys. The current era of smartphones offers easy solutions, such as installing applications (Apps for short) that use the built-in electronic sensors of the phone set to measure phenomena such as sound, light, or motion efficiently. A phone's microphone aids in examining the loudness of different sounds in the environment (Finio, 2019). This study adopted an Android app on a mobile phone and a handheld sound meter alternately for measuring urban sounds. Both were tested for accuracy and uniformity in displaying scores and were found to render the same readings, with a negligible 0.06% variation in the pilot assessment. Hence, both suited the purpose. The study suggests that the age of the phone has a bearing on its ability to measure noise accurately (Murphy and King, 2016); accordingly, the survey adopts a smartphone set of fewer than three months in usage.
As applicable derivatives and learnings from the literature on sound mapping techniques, the research methodology adopts a mixed method research of quantitative and qualitative assessment techniques with convergent parallel design of data collection to review urban acoustical scenarios through field surveys and opinion surveys. Mainly, references that offered reliable and consistent perspectives include- smartphone applications and focus group discussion surveys (Can, Audubert et al., 2023), the adoption of smartphone microphones for assessment (Finio, 2019), outdoor environmental acoustic assessment adopting varied levels of sound perceptions (Jo and Jeon, 2021), and intelligent tools for noise mapping towards urban development purposes (Vogiatzis and Remy, 2019). The study thus formulates a methodological triangulation that relies on three aspects of data collection in the study neighborhoods-
The study was conducted in Bangalore in southern India, popularly known as the Silicon City of India and a fast-growing city on the global map. It is also known as Garden City and Pensioner's Paradise, as it was once a city of calm and natural beauty. Urban developmental activities in the nearly 750 sq km spread city lead to water, air, and noise pollution. In a study, the noise levels measured at ten Continuous Noise Monitoring Stations in Bangalore city for September 2023 revealed a sharp rise between 12.7% to 87.3% (this was noted in a silent zone closer to an educational institution) compared to the permissible limits (KSPCB, 2023) revealing noise level breach in most places post the pandemic lockdown years (Deccan Herald News, 2022).
The types of neighborhoods in Bangalore generally fall into two broad categories. The first type involved mixed-use residential with commercial or institutional uses, which are modest, of diverse socio-cultural and economic populations, and the second type is exclusive residential zones, which are either gated communities with villas or high-rise apartments with basic amenities within their premises. The first typology is chosen in this study, as these are predominantly witnessed in the city as per Bangalore Master Plan land use document (B.D.A., 2015) and are multi-use zones active during the entire day. Accordingly, the two neighborhoods of study, Vijayanagar and Basavanagudi, represent most city neighborhoods and yet individually have definite characteristics.
The primary data collection involved field surveys called soundscape audits (Figure 2). Sound level meters and smartphone applications became alternate tools for quantifying noise levels along the neighborhood study streets.
The qualitative assessment was achieved with opinion-based surveys. Two modes of inquiry are adopted- an online questionnaire survey and an in-person interview (Figure 3). The online survey involved an online Google form involving people's perspectives in a generic sense and not city-specific essentially. Under the in-person interview surveys, a ‘3-Test’ method with specific objectives to assess noise levels was formulated:
The 'Identify test' involved a hierarchical three-tier probing on opinions about what contributes to the noise along their neighborhood streets: first level instinctive listing of most evident sources of noise, second effortful thinking for next set of responses, and third further emphasized or stressed-upon thinking. Under the 'Distance test,' an additional aspect assessed was the spatial distance at which the person could hear his companion or interviewer speak in the case of respondents from the public space category. The 'Earphone test' involved authors themselves listening to music or talking on cell phones using ear pods and walking 400 m cruising along the residential and mixed-use streets in the two neighborhoods, noting down if and how many altercations in audio levels are necessary for ambient listening in response to street level noise.
Quantitative results from the soundscape audit surveys and qualitative results from the online opinion surveys and interview tests are presented in this section. However, at the outset, based on one of the understandings required in the study being auditory profiles of urban spaces, it becomes necessary to perceive the different types and sources of ubiquitous urban noise. Schafer classified sounds into six categories: natural, human, societal (domestic sounds), mechanical, quiet, and indicators (horns, whistles) based on literary, anthropological, and historical databases (Aiello, Schifanella et al., 2016). The two significant settings (Berglund, Lindvall et al., 1999) where noise occurs are community noise and industrial noise; the former is also referred to as environmental noise, residential noise, or domestic noise, with significant sources being automobiles, construction work, loudspeakers, recreational activities, or fireworks. Likewise, in this research, sounds are classified broadly as natural and artificial and as positive (desired), negative (undesired), or subjectively perceived sounds.
Positive sounds (desirable):
Negative sounds (undesirable):
Subjectively perceived (temperamental) sounds:
Relatively, the urban spaces that contribute to noise and classification based on the sources of sound pollution are perceived based on general contextual observations in the study scenarios (Table 1).
| Sl. No. | Sources of noise | Urban spaces contributing to noise pollution |
|---|---|---|
| 1 | Motor vehicles |
Streets, Junctions & Squares Transit nodes- Bus stops/ metro stations/ railway stations/ airports Markets Parking zones Commercial zones |
| 2 | Mechanical processes |
Road works Construction activities- public or private Vehicle garages Factories Air conditioning units/ plants Generators Loudspeakers/ Sirens |
| 3 | Public gathering and crowd activities |
Parks, Squares, Plazas, Playgrounds Markets/ Malls Cultural nodes Public events/ gatherings/ Firecrackers Residential localities- Houses/ apartments Institutional zones- Schools/ colleges |
Further, the results from the field and opinion surveys become based on either one or a combination of the above types of sounds, lending perceptions to soundscape assessments.
Soundscape audit resultsThe delineated study areas in both neighborhoods were approximately 0.5 to 0.8 sqm km (square quarter mile) extent, comprising nearly 10 to 12 significant streets, with 40% of such streets chosen for detailed survey. Hence, the sample set comprised five streets from each neighborhood - five alternate streets in Vijayanagar and five of every 4th street in Basavanagudi derived from the structure of the neighborhood. Two are predominantly residential streets, and three are mixed-use streets (residences and commercial or public land uses) (Table 2 & Figure 4). In Vijayanagar, the chosen streets lie between two main commercial roads with an intersecting mixed-use road, while in Basavanagudi, the streets connect to two central active spines (Table 3 & Figure 4). The survey was conducted in September 2021, a favorable outdoor weather time during weekdays and weekends for every 3 hours, from 6.00 AM till 9 PM. Each of these times, calibration of five readings at 10-minute intervals at a reading spot in the middle of the street stretch was undertaken. Secondly, the sound level mapping exercise was undertaken across all the study area streets with three readings along each street in the peak mornings between 9 AM and 11 AM, five times during the month (Figure 2).
| Street No. | Street name | Land use majorly |
|---|---|---|
| S1 | 1st Main Road | Residential |
| S2 | 3rd Main Road | Residential |
| S3 | 6th Main Road | Mixed-use (Residential + Public) |
| S4 | 9th A Main Road | Mixed-use (Residential + Public) |
| S5 | 12th Main Road | Mixed-use (Residential + Commercial) |
| Street No. | Street name | Land use majorly |
|---|---|---|
| S1 | D V G Road (a) | Residential |
| S2 | Ranga Rao Road | Residential |
| S3 | K S Road | Mixed-use (Residential + Public) |
| S4 | 2nd Main Road | Mixed-use (Residential + Commercial) |
| S5 | D V G Road (b) | Mixed-use (Residential + Commercial) |
The soundscape audit surveys in the two neighborhoods of Bangalore were analyzed in terms of day-wise average (Table 4) for each of the five streets surveyed in each study area and week-wise average (Table 5) for the month of investigation.
| AVERAGE SCORES DAYWISE (dB) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| VIJAYANAGAR | BASAVANAGUDI | |||||||||
| Streets > | S1 | S2 | S3 | S4 | S5 | S1 | S2 | S3 | S4 | S5 |
| Monday | 80 | 87 | 102 | 100 | 98 | 82 | 87 | 100 | 96 | 92 |
| Tuesday | 75 | 90 | 100 | 103 | 104 | 95 | 90 | 101 | 98 | 86 |
| Wednesday | 95 | 90 | 98 | 102 | 102 | 90 | 88 | 98 | 101 | 88 |
| Thursday | 90 | 88 | 95 | 88 | 89 | 80 | 68 | 100 | 103 | 104 |
| Friday | 75 | 75 | 101 | 98 | 86 | 89 | 82 | 98 | 102 | 102 |
| Saturday | 89 | 82 | 98 | 101 | 88 | 100 | 88 | 98 | 103 | 90 |
| Sunday | 100 | 88 | 98 | 103 | 90 | 89 | 100 | 95 | 88 | 89 |
| AVERAGE SCORES WEEKWISE (dB) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| VIJAYANAGAR | BASAVANAGUDI | |||||||||
| Streets > | S1 | S2 | S3 | S4 | S5 | S1 | S2 | S3 | S4 | S5 |
| WEEK 1 | 88 | 75 | 100 | 102 | 97 | 80 | 88 | 98 | 88 | 98 |
| WEEK 2 | 80 | 98 | 98 | 102 | 102 | 78 | 89 | 102 | 80 | 88 |
| WEEK 3 | 100 | 95 | 99 | 101 | 89 | 75 | 95 | 98 | 103 | 96 |
| WEEK 4 | 98 | 85 | 98 | 100 | 102 | 80 | 100 | 85 | 85 | 80 |
The daily sound level average was 92.97 dB, while the weekly average was 92.38 dB. The mixed-use streets reflected an average daily average of 97 dB in Vijayanagar and Basavanagudi each, while week-wise average scores were 99 and 92. The predominantly residential zones showed day-wise averages of 93 and 88 and week-wise averages of 90 and 86 for Vijayanagar and Basavanagudi, respectively.
The sound level mapping exercises (Figure 5) revealed a pattern of occurrence w.r.t the spatial locations. Levels along the middle of tertiary streets (9 or 12 m wide) seem lower than at the street ends closer to junctions meeting with primary roads. The merger of traffic at junctions and excessive honking elevated the levels. Also, bigger motors such as school buses, public transport buses, and rickshaws plying along main roads radiate more noise onto narrow streets. Even with a single vehicle passing by, they steeply hiked the levels to over 100 dB. Additionally, nodes such as metro stations, shopping marts, banks, or shopping zones trigger targeted traffic collation and activity buzz. Accordingly, in the study, five main influencing parameters contributing to noise levels are thus deduced, namely, land use, street widths, junctions, traffic, and activity nodes.
Weekly day-wise average noise levels displayed a steep variation across the days of the week. Mid-week Wednesdays and Thursdays recorded higher values, while Mondays, Tuesdays, and Fridays showed lower values than other days. Across weekends, Sundays were the quietest, especially from 10 AM to 4 PM in the neighborhoods, offering a good respite (Table 6). Mid-week phenomena were attributed to all workplaces, businesses, and institutions functioning fully and contributing to traffic and activity levels (Philip, 2024).
| AVERAGE SCORES DAY-WISE (dB) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| VIJAYANAGAR | BASAVANAGUDI | ||||||||||
| streets> | S1 | S2 | S3 | S4 | S5 | S1 | S2 | S3 | S4 | S5 | Av scores |
| Monday | 80 | 87 | 102 | 100 | 98 | 82 | 87 | 100 | 96 | 92 | 92.4 |
| Tuesday | 75 | 90 | 98 | 103 | 104 | 95 | 90 | 101 | 98 | 86 | 94.0 |
| Wednesday | 95 | 96 | 98 | 102 | 102 | 90 | 98 | 98 | 101 | 88 | 96.8 |
| Thursday | 90 | 96 | 95 | 102 | 98 | 100 | 89 | 100 | 103 | 104 | 97.7 |
| Friday | 75 | 75 | 101 | 98 | 86 | 89 | 89 | 98 | 102 | 102 | 91.5 |
| Saturday | 89 | 82 | 98 | 101 | 88 | 100 | 88 | 98 | 103 | 90 | 93.7 |
| Sunday | 88 | 88 | 98 | 90 | 90 | 89 | 79 | 89 | 88 | 89 | 88.8 |
Further, across a given day of the week, average noise levels peaked between 8 AM to 12 PM and 5 PM to 10 PM. On weekends, Saturdays, and Sundays, noise levels increase beyond 9 PM up to 11.30 PM, while middays are quiet comparatively. These observations are attributed to weekend late-evening active spurs in most eating outlets in the city and return travels by people from their weekend outings. However, when looking at individual street values, spots of non-routine activities such as construction, road works, and people gathering deviate from the average scores by 5% to 10%. Land use in the neighborhood becomes a critical parameter; businesses and commerce beyond a certain degree in residential zones contribute to elevated noise levels, which must be more conducive to the public realm and liveable quality. Not all instances of noise pollution are spot-specific but majorly have a hierarchical bearing as a chain occurrence from a regional level. Thus, Planners must analyze urban planning and design factors leading to noise generation concerning the five noted parameters: land use, street widths, junctions, traffic, and activity nodes.
The results obtained from the soundscape audits become one data set in the research as observed and interpreted in the surveys. This data is co-related with the government-stipulated norms that are in place for noise levels in Indian cities. The stipulated thresholds become a benchmark for the assessment of observed parameters. The Noise Pollution Rules (CPCB, 2000) specify ambient noise limits in various land use zones for residential areas as 55 dB(A) Leq during daytime and 45 during night-time. Meanwhile, surveys conducted in the study reveal values much beyond permissible ranges, reaching up to 105 during the daytime (Table 6). This phenomenon points to severe concerns and triggers thoughts on neighborhood acoustic health. Noise is an imperative factor, but it needs a more holistic approach to assessment and regulation. The legislation specifies specific guidelines on noise control, but the implementation measures to ensure enforcement are an observed gap and point towards future research on the same.
The online questionnaire (Google form) was floated on social platforms such as ResearchGate, LinkedIn, and Academic Circle, with one hundred valid responses registered between February and March 2022. Sample sizes larger than 30 and less than 500 are appropriate for most research (Sekaran and Bougie, 2016); a minimum of 100 was considered sufficient to proceed with the study, eliminating the invalid responses.
Of the responses received, 75% were residents of mixed-use neighborhoods. 35% of respondents conveyed that the average sound level on their streets was three on a scale of 1 to 5, with 5 being the highest. The total number of respondents conveying levels 4 and 5 was 32%. On the query on what reasons contributed to noise pollution that created discomfort, the top reasons were traffic, dogs (street strays) barking, and construction activities among the listed options (Table 7).
32% opine that street-level noise induces botheration, such as disturbing the peace and hindering activities such as reading, watching T.V., and sleeping. Whereas, specifically, from Bangalore city dwellers, of the 46 valid online responses received, 68% expressed that sound levels on their streets disturb the peace and hinder activities such as reading, watching T.V., and sleeping. Amongst this, 72% dwell in mixed-use neighborhoods, and the rest in exclusively residential areas. Hence, the city projects higher levels of noise impact on residents.
Loss of concentration, uneasiness, irritation, and headache are the top reasons for the impact of sound pollution on one's physiology. 62% of opinion points at street level noise impacting lifestyles in various concerning ways. 70% of respondents expressed health-related concerns. The opinions convey the underlying urgency in understanding urban health in response to urban noise. Hence, urban acoustical ecology has become a priority and poses an immediate need to address urban noise issues and aspects of liveability in residential zones.
The ‘3-Test’ survey resultsThe in-person interviews were conducted in July 2022 along the five streets of the study neighborhoods, with a random sampling method involving every third house on the street, which had anywhere between 15 to 25 houses along each. When streets had a public space such as a park or a retail shop, the authors approached users willing to respond to the questionnaire. At least one hundred persons were successfully interviewed, 70 from residences and the rest from the public space user group. In total, 200 valid opinion responses were analyzed across the opinion surveys.
The outcome from the three tests, namely, the identity test, distance test, and earphone test, lent perspectives on reflexes and responses to sound by people in their neighborhoods. Firstly, the ‘identify test’ sees the responses under three stages (Table 7), giving insight into exposure to noise sources and individuals' tolerance/ perceptive response levels. It also showed that people are generally accustomed to urban sounds and tend to be psychologically adapted to the same without consciously being aware of the noise.
| Probe level | Responses for sources of noise | % response | Inferential |
|---|---|---|---|
|
First (Instinctive) |
Motor vehicles – honking, engine, sirens | 96% | Evident/ obvious noises |
| Construction activities | 88% | ||
| Crowding-related activities | 75% | ||
|
Second (Effortful thinking) |
Noise from streets other than motors | 88% | Situational/ occasional noises |
| Public events/ loudspeakers | 76% | ||
| Dogs (strays) barking (especially at night times) | 70% | ||
|
Third (Stressed thinking) |
Noisy neighbors/ kids | 78% | Routine/ accustomed noises |
| Domestic activities (Washing/ sweeping) | 60% |
Secondly, two aspects were noticed under the 'distance test' conducted in open public spaces, mainly streets and parks. Firstly, distance had to be maintained ideally between one to two feet for a regular intensity dialogue during the conversation. Secondly, the frequency of conversation in the same tempo- this was seemingly interrupted by sounds of considerable loudness enough for the listener to strain their ears to hear or the speaker to either pause speaking or speak up louder. Sound sources included a vehicle, a vegetable vendor with his microphone announcing system, or conversing passers-by. The observations across a 5-minute conversation were recorded, and scores were analyzed, with results indicating a definite need for persons to maintain closer proximity to enable legible hearing.
Thirdly, the 'earphone test' undertaken by the authors revealed the impact of noise pollution rather evidently, by the consistent need to increase audio volumes to listen better along mixed-use streets with heavier traffic where sound meter app levels were over 85 dB, audio levels at which the phone app displayed a message that observed levels did not fall under the recommended ranges of the safety of ears. In this walk spanning over 10 minutes, the observations revealed that on average, 5 to 8 times, the audio needed adjustment to lower or increase audio intensity as quieter or noisy stretches passed. The results helped to perceive the degree of fluctuation of sound levels along streets, which was consistently high.
The study involves experiments with the two variables of sound levels and streetscapes in the selected neighborhoods' point at noise strongly influencing the liveability of the neighborhood, asserting the hypothetical proposition. Based on these observations and findings, the study aims to derive an urban acoustical ecosystem by addressing the impending noise and resolutions in the urban planning scheme of action for achieving acoustical resilience through strategic proposals for 'Urban acoustical resilience.'
As per the ‘Theory of Complexity’ that focuses on acoustic complexity or sonic diversity (Ipsen, 2002), it is suggested that when the complexity of information is low, the situation becomes less attractive. In contrast, when the complexity is very high and unreadable, the person reacts with annoyance. Hence, an intermediate level of complexity is advisable, which generates a high level of positive motivation. In case of familiarity with a situation, information input gets less complex, and an individual's adaptability level will influence his response to that acoustic information. Thus, soundscapes are subjective, whereas cities bear diverse acoustical complexity. 100% silent cities are hypothetical, yet urban noise can be effectively designed and managed with proper application in city designs. For instance, the theory suggests the adoption of an appropriate balance of Geophony (sounds generated by natural physical processes such as water, wind, and rain) and Biophony (sounds generated from non-human organisms) (Ipsen, 2002). The method of community planning must involve the construction of a robust natural environment comprising green zones or water bodies to enhance the ecological impact of the community environment and improve residents' well-being in all ways (Cao, Yang et al., 2024).
An integrated approach to urban noise is proposed herein, where acoustic ecology, urban planning, design, landscape architecture, ecology, acoustics, psychology, innovative design, and transport planning derive holistic resolutions. While visual parameters are the main criteria, urban streets become multi-sensorial, involving sound, smell, and taste perceptions influencing pedestrians' itinerary choices (Boumezoued, Bada et al., 2020). Soundscape design is crucial in current times to create sustainable and pleasant habitats. For example, studies show that green walls can reduce up to 40 dB of outdoor noise and vibration in buildings if properly designed and executed. Urban spaces must present pleasant acoustic environments appreciated and enjoyed by everyone as healthier havens rather than health-impacting polluted zones. Street-level noise in urban spaces contributes majorly to overall noise pollution and should be prioritized and reduced in urban planning for better public health (McAlexander, Gershon et al., 2015).
Hence, based on the understandings from literature and findings from the primary audits, two aspects are deduced for liveable and sustainable neighborhoods– one, to plan acoustically ambient streetscapes and second, to formulate a supporting mechanism to regulate noise levels. It recommends strategic proposals under two broad aspects of ‘design’ and ‘regulatory mechanism’ as suggestive frameworks.
The five parameters deduced from the audit results become the basis for proposing a ‘five-point strategy for design’ of acoustically ambient urban environs (Figure 8). Such a framework is envisaged as a suggestive guideline to embed noise as a parameter to direct urban planning and designs. Each parameter beckons a detailed future study for in-depth derivations of resolutions to achieve amicable urban acoustics toward noise isolation.
Further, the study of noise legislation and co-related with audit results showed a definite gap in the holistic implementation to sustain safe thresholds. Hence, to enable this, a ‘three-point strategy for a regulatory mechanism’ is proposed to encompass post-design implementation aspects of audit and assessment of performance for closing the loop towards a sustainable system (Figure 9). A rigorous 'audit and action' plan is essential for the continual evaluation and responsive mitigation measures to maintain a favorable threshold of sound levels as a cyclic process. This framework, sustained with a participatory approach and citizen engagement with 'awareness' drives, enables an efficient roadmap to achieve safer and calmer neighborhoods.
A well-coordinated action plan to address air and noise pollution with collectively charted mitigation measures becomes a value-added strategy. City plans with effective zoning are an essential start-off point for resolving many urban issues, one that envisages residential neighborhoods with minimal car usage or noisy traffic zones. To achieve urban acoustical resilience, ‘Noise maps’ as ready reckoner databases must be encompassed in City Plans (Kumar, Chauhan et al., 2022) to document, analyze, and resolve noise pollution. The most evident solution with proven results is the landscape design schemes that adopt appropriate green covers and buffers to absorb or diffuse noise and dust alike while creating required degrees of privacy to spaces by way of green roofs, green walls, or green belts that enhance biodiversity. Newer innovative engineering solutions provide and ascertain definite solutions towards built form and urban public space designs to enable sonic screens and acoustical regulations to the urban habitats. Resorting to naturally available local building materials and vernacular techniques in shaping public spaces go a long way in achieving social and environmental sustainability.
The study attempted to inquire about the concern of sound as a parameter for planning and designing urban spaces and neighborhoods for ambient acoustical experiences. Towards this, understanding the fundamental concepts of the impacts of noise pollution on liveability, perceiving the magnitude of the concern, and reviewing soundscape theories and sound measuring concepts were reviewed. The literature revealed the impact of noise pollution on the overall physiological and psychological well-being of people and, hence, the liveability of the neighborhoods. The study was conducted in Bangalore in Southern India, in the Asian subcontinent, to test the premise. Most cities in India are heavily populated, with dense neighborhoods, mixed-use developments, and varied activities, resulting in heavy traffic and evidence of heavy noise pollution in several cities ( UNEP, 2022). However, with limited research on the acoustics of urban spaces, this study triggers relational perceptions between spatial planning and noise attributes.
The audit methodology formulated in this study, which is a triangulation of field surveys, interviews, and questionnaire surveys, identifies residents' prevalent noise ranges and perceptive tendencies and their impact at various levels. The field audits using sound meters and smartphone Apps deduced values of noise levels beyond the safe ranges as suggested by the World Health Organization and thresholds laid down by various legislations. The scores indicate a steep difference, with prevalent levels being over and above the norms by nearly 200% compared to stipulated norms.
The study lays out a vision for liveable neighborhoods that are sonically adept, with strategic proposals deduced for ‘Urban acoustical resilience’ as generic suggestive action plans for city development to tackle the challenges while understanding where the focus can be advantageously placed. The proposed acoustical resilient strategy can be suitably applied in cities in India, Asia, and any other country across the world that is facing concerns about noise pollution. The outcomes suggest that cities must incorporate 'sound' as an insinuating factor in the planning and design resolutions of their urban spaces, such as streets, markets, plazas, and public nodes, to create holistic acoustical realms for healthy cities. Hence, the suggested trans-disciplinary study between urban design and urban acoustics shall enable the goals of achieving safe 'sounding' cities for its people when they are within their homes or in the public spaces of their neighborhoods.
Conceptualization, methodology, M.P.R. and D.R.P.; investigation, resources, D.R.P.; data curation, writing—original draft preparation, D.R.P.; writing—review and editing, final draft, M.P.R.; supervision, M.P.R. and D.R.P. Both authors have read and agreed to the published version of the manuscript.
The authors declare that they have no conflicts of interest regarding the publication of the paper.
The authors acknowledge the co-operation rendered by all the respondents during the questionnaire surveys and interviews for their valuable inputs. And appreciate the resources provided by Library and Laboratories at BMS College of Architecture.
