managing the urban acoustic environment: from noise ... · from noise control to soundscaping. ......

Lam Kin Che 林健枝 Director, Institute of Environment, Energy and Sustainability Professor, Department of Geography & Resource Management The Chinese University of Hong Kong

Hong Kong EPD 25 Anniversary Public Seminar

Environmental Protection in Hong Kong: Past and Future

27 October 2011

Managing the urban acoustic environment:

from noise control to soundscaping

Sound – An important but often neglected

element of the Urban Environment

• The noise which we dislike

• “Willingness to pay” for one‟s own “sound

bubble”

Outline of Presentation

• Noise is a health issue

• Conventional approach to managing the urban

acoustic environment

• New paradigm – The soundscape approach

Noise – not just a feeling of discomfort

Annoyance

• Annoyance

– “…a feeling of resentment, displeasure, discomfort,

dissatisfaction, or offense when noise interferes

with thoughts, feelings, or actual activities.”

• Annoyance at High Noise Levels

– “…should be considered a legitimate environmental

health issue affecting the wellbeing and quality of

life of the population…”

UK Health Protection Agency, 2009

The Stress Model: Mechanism of Noise

Induced Health Effects (Babisch et al, 2001)

Noise is a Health Risk

• Supported by clinical

studies in last 20 years

• Ascertained by several

large scale surveys

WHO, 2011

Noise-related Health Risks Compared

with Others (Van Kemp, 2010)

• Changes are faster than we can document them

• Conventional monitoring data do not provide all

relevant information, most are expressed in dB levels

Rapid Changes of the Acoustic

Environment

• Noise as a health issue

• Conventional approach to managing the urban

Exposure of Hong Kong

Population to Road Traffic Noise

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

No. of People

Source: HK EPD

No. of People Exposed to Road

Traffic Noise Levels > 70 dB(A)

20,000

40,000

60,000

80,000

100,000

120,000

140,000

Source: HK EPD

Conventional Approach in Hong

Kong and Many Other Cities

• Noise standards expressed in simple metrics,

e.g. LA10 & LAeq

• Noise reduction at source

• Noise planning

Basics of Noise Control

1 Source

Strength 2 Noise

Path 3 Receiver

Source: HK EPD

Low Noise Road Resurfacing Scheme

• Reduce noise emission up to 3 dB(A) when new

• Building cost: about HK$100 – HK$120 per sq m, double that of

normal

• Maintenance cost: about HK$40 – HK$50 per sq m, five times more

• Efficiency drops over time

Limitation of Using Noise Screening

Structures to Reduce Noise

• Little space in Hong Kong for noise to

attenuate

• Barriers have limited effects in high-rise cities

• Increasing cost per dwelling/ per dB reduction

• In some hot spots, the noise criterion is

exceeded by many dB

How Many Cars Have to be Removed?

• Assuming the noise criterion is LDEN 65 dB(A)

To reduce

noise by 3 dB,

traffic flow has

to be cut by

Noise Planning is Called for …..

“Planning against transportation noise in a

metropolis like Hong Kong is definitely not

an easy task. However, if we focus on

potential noise problem at the very outset of

planning, we can have a high probability of

meeting the noise exposure standards as

set out in the Hong Kong Planning

Standards and Guidelines (HKPSG).”

Source: HKPSG

EPD Good Practice Guides on

Noise Planning

Screening Structures and Building Designs against Transportation Noise in Hong Kong

http://www.epd.gov.hk/epd/english/environmentinhk/noise/guide_ref/screen_stru.html

Housing Design to Abate Traffic Noise in Hong Kong

http://www.epd.gov.hk/epd/english/environmentinhk/noise/guide_ref/hous_design.html

Critical Question 1: Can we really reduce

annoyance by reducing noise?

• This can only be ascertained by establishing the

noise exposure – effects curve based on large

scale study.

• There are several such studies in the world.

Using Exposure – Effects Curve to

Inform Standard Setting

Influence of Slope of Exposure-

Effects Curve on Annoyance

Noise Level 0

City X

Miedema Curve

Critical Question 2: Are people annoyed at home or outside their residence?

• Dwelling

• Neighbourhood

• Community

Dwelling

Neighbourhood

Community Level

Neighbourhood

Change in Noise Exposure LA10 Over Time in HK – Public Housing

Source: Lam in press

Change in Noise Exposure LA10 Over Time in HK

– Private Housing

Source: Lam in press

• Noise as a health issue

• Conventional approach to manage the urban

Managing Urban Transportation Noise

• Not merely by noise reduction, but by

Managing the adverse effects of noise,

such as annoyance and sleep disturbance

• Not just reduce unwanted sound, but

Incorporate wanted sound in urban design

Mask unwanted sound by wanted ones

Significance of “Restorative Environment” in the City

• Respite from urban stress • Rejuvenation • Different from daily chores

“You go to Central Park to escape,

you come to the High Line to be

elevated.”

- A Park User in Manhattan

“Soundscape” Approach

• “Sound …..” – A “neutral” term

– Meaning to the listener

– People-centered

• “….. Scape” – Totality of the acoustic environment

– Human experience is multi-sensory

– Context specific

Soundscape Conceptual Framework

Wanted and Unwanted Sound in Cities

• Unwanted - Noise

• Road traffic

• Industries

• Wanted

• Bird songs

• Water sound

• Nature/wilderness

• wildlife protection

• human appreciation/ well-being

• Countryside/recreation

• Urban

Sound Preference is “Place” specific

Source: Lex Brown

Noise Control vs Soundscape Planning

Noise Control

Concerns sounds of discomfort

Usually measured by

integrating sound metrics (Leq)

Manages by reducing levels

Sound as a waste

Noise Control Soundscape Planning

Concerns sounds of discomfort Concerns sounds of preference

Usually measured by

integrating sound metrics (Leq) Differentiates between sound

sources (wanted and unwanted)

Manages by reducing levels Manages by wanted sounds &

masking unwanted sounds

Sound as a waste Sound as a resource

Noise Control vs Soundscape Planning

Increasing emphasis on

soundscape activities

• Importance increasingly recognized by government and

organizations in Europe – Noise network in the UK and 3+ associated projects

– „Soundscape support to health‟ project in Sweden

– Soundscape projects funded by the French Ministry of Town

Planning, Housing and Construction

– DoE & DEFRA, U.K.

• Increasing interests in practice – Greater London Authority

– City of Berlin

– Archaeological places in Italy

– City of Antwerp, Belgium

2009 U.K. DEFRA Monograph

Drivers of Change

• EU Environmental Noise Directive

END requires “… preserving environmental noise quality where it is good …”

Attention given to “Quiet Areas”

• Value of National Park/Wilderness to Urban Inhabitants

Recreationist‟s experiences/conflicts

Effects of human activity on wildlife

• Recognition of limitation of conventional noise control practices

Significance of a wetland park to Residents

of nearby high-rise apartments

Reedbed

Spur Pond

Mudflat

Woodland

Wetland Discovery Centre

LRT Wetland Park Station

Phase 1 venue of HKWP

Restorative Environment - Urban Park

Soundscape Design at Nan Lian

Garden

• Landscape/Soundscape

design

– Noise screens

– Water structures

– Sound emulation

– Attention “refocusing” –

“mind masking”

What does the literature say about non-

acoustic factors affecting annoyance?

• Access to “quiet side” inside the dwelling

• Availability of nearby “restorative”

environment

• Good neighborhood environment

• Masking – acoustic and mental masking

Protecting quiet areas rather than

reducing noise levels

• In addition to exposure mapping and the preparation of action plans, the END requires “… preserving environmental noise quality where it is good …”

• This has lead to significant activities and attention to “Quiet Areas”

EU Environmental Noise Directive (2002/49/EC)

A Change in Paradigm Needed

• Goal

– Pursuit of high acoustic quality rather than mere

quietness

• Objective

– Not low Level (Leq or Lden) but “wanted sounds” heard

over “unwanted sounds”

• Approach

– Not just noise reduction, but masking

– Managing human annoyance and expectation

Today’s Takeaway - 1

• Sound is a vital component of urban living:

– Health issue

– Quality of life

• Conventional approach has severe limitations:

– Practical difficulties

– Cost-effectiveness

Today’s Takeaway - 2

• Need for a paradigm shift:

– Preservation of quiet areas

– Access to restorative environment

– Planning sound as a resource

• Change in approach:

– Focus on adaptation, rather than merely mitigation & reduction

– Managing annoyance reaction rather than merely reducing noise

Soundscaping

The “sound” approach

to managing the urban

acoustic environment !

Welcome to Acoustics 2012 Hong Kong 14-18 May, 2012

Kin-Che LAM 林健枝 HonFCIWEM, FHKIEIA, MHKIOA, SBS, JP

Email: kinchelam@cuhk.edu.hk

Significance of Sound with the “Context”

• Congruent with the

• Place

• Activities

• Expectation

• Congruence ensures that

• Sound adds human enjoyment/satisfaction

• Activities/expectations are not being interfered with

Which Noise Annoys People in HK?

“Highly Annoyed” = 8 to 10 on 0 to 10 scale

Challenge of Building Urban Park in A

Compact City

Digital Model

• Railway tracks

• Road centreline

• Airport

• Building footprints

• Podiums

• Barriers

• Enclosures

• Spot heights

• Contour lines

• Rivers

• Slope tops/bottoms

• Vegetation (ground

absorption)

Propagation Path

Input Processing Output

Emitters

• # of vehicles

• Speed

• Vehicle weight

Traffic Model

Exposure

Software

Calculates noise levels in different areas using inputs

Level of

exposure

estimated for

various areas;

3-D visualization

Obtain façade

noise exposure of

over 10,000

addresses

Technique of Noise Mapping

63 – 67

60 – 63

Leq (1-hour)

Example of Modeling Results

Which Noise Sources Annoy?

• “Highly Annoyed” = 8 to 10 on 0 to 10 scale

Comparing the HK Exposure - Highly

Annoyed Curve with Miedema’s

Noise Level 0

Noise Exposure – Effects Curve

Noise Level 0

Hong Kong

City X

Statistical Analysis

• Binary logistics ordinal regression

Binary: Highly Annoyed (HA) / Highly Sleep Disturbed

(HSD) or not?

• With respect to road traffic noise

24h (LDEN) & at night (LNIGHT) respectively

• Key predictor variables

Noise exposure - LDEN, Lnight

• Confounders (ordinal)

From previous studies & theory, to be described in next

Confounders

• In addition to “noise exposure” - 24h (LDEN) & at

night (LNIGHT)

• Physical factors affecting noise exposure

Access to quiet room; closing window; crowdedness, number of

households in quarter

• Factors affecting perception/response

Satisfaction with neighborhood environment, ownership, quarter

type, year of residence

• Other personal factors

Noise sensitivity, hearing problems, poverty, gender, age,

employment, shift-worker, education level, occupation, monthly

household income, sleep outside curfew, sleep deprived

• Results of binary logistic ordinal regression

Factors Affecting whether the

Respondent is Highly Annoyed

Odds Ratio

Factors Affecting whether the Respondent

is Highly Sleep Disturbed

• Results of binary logistic ordinal regression

Odds Ratio

Summary Findings

• Noise exposure has positive but limited

effects

• Factors are similar for “highly annoyed” and

“highly sleep disturbed” responses

• Intensification factors: noise sensitivity

• Moderating factors: access to quiet room,

satisfaction with neighborhood

Implications for noise management &

planning

• Managing annoyance rather than noise reduction

• Protection quiet areas rather than limiting noise

levels

• Creating a good “total environment” rather than

reducing noise exposure at the “dwellings”

Factors Affecting Annoyance

Response

• Intensify annoyance

– Ill-heath

– Noise sensitivity

• Moderate annoyance

– Satisfaction with neighborhood

– Access to a “quiet room”

Total environment

• Creating a good “total environment” rather than

reducing noise exposure at the “dwelling”

Annoyance from various noise sources

• Human annoyance – Non only determined by

transportation noise

– But a range of non-transportation noise sources

– e.g. Renovation noises, neighbourhood noises, construction noises

• Varies among various urban forms in Hong Kong

Annoyance Management

• Transportation noise is only one of the many causes of annoyance

– Renovation, neighbourhood, construction noises etc.

• Factors mediating annoyance – Other factors in the entire enviro-scape

(Schulte-Fortkamp, 2000)

– Provision of other greenery/ open space (Gidlöf-Gunnarsson and Öhrström‟s, 2007)

– Design of urban forms (This Study)

Design of urban forms

Puzzle for the Environment Manager

• How should the standard be set?

• Is the current approach effective?

• What are the policy options?

Managing Annoyance vs. Noise

Reduction

• Need to find out what can moderate or attenuate

annoyance response

• To intervene by Improving neighborhood environment

Providing quiet side/room in dwelling

Creating positive soundscapes

•To reduce noise by 3 dB, traffic flow

has to be reduced by half

Living Space of the Hong Kong People

• Dwelling

• Neighbourhood

• Community

Dwelling

Neighbourhood

Community Level

Neighbourhood

Noise Exposure Levels at and in the vicinity of Home

Dwelling Level

Neigbhourhood Level

Community Level

SH Small houses OS Old development with squares ON Old development and small housing estates without podium CM Compact massive housing estates LN Large housing estates without podium LP Large housing estates with podium

• Coping Behaviour

– Enjoying the sound

– Shutting the ear

– Creating one‟s own “sound bubble”

– Escape into a quiet room or place

– Doing something that is “insensitive” to noise

How do people cope?

• Soundscape is continuous & relatively stationary

• Human beings are discrete & mobile – Activity space

– Mental space

• Human movement – Necessity

– Choice

Humans in the Environment

Uncertainties in the Health Effects of

Noise Awaiting our Investigation

• Annoyance

Culture related?

Effects of coping behavior?

Response of residents of compact cities?

• Sleep Disturbance

Applicability of European noise limits to Asian

countries?

Challenges of Managing the Urban

Acoustic Environment

• How should noise standards be set?

• How effective is the current approach?

• What options are available to us?

• To what extent policy is evidence-based?

Soundscape – More than

Numbers and Parts

“Soundscape evaluation is a holistic

perception, not a sum of the

evaluation of the acoustic

properties of sound sources. ”

• Human experience is multi-modal, with all senses

• Each sense reinforces the others

• Objectivity of “seeing” – “Seeing” as an onlooker, less

emotionally involved

• We can see what we do not hear; we can hear what

we do not see

Perceiving the Environment with all

the Senses

Limited Effective to Reduce Annoyance if

the Curve is Flat

Noise Level 0

managing the urban acoustic environment: from noise ... · from noise control to soundscaping. ......

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