acoustics of building architecture

1. BUILDING SERVICES IV ACOUSTICS & NOISE CONTROL - 18 ARC 7.3
MODULE 5 – NOISE REDUCTION AND CONTROL II

2. 18 ARC 7.3 BS IV
18ARC73- BUILDING SERVICES – IV(ACOUSTICS AND NOISE CONTROL)
CONTACT PERIODS : 3 (Lecture) per week
PROGRESSIVE MARKS : 50
DURATION OF EXAM: 3 Hrs THEORY MARKS : 100
OBJECTIVE: To explore the role and capacity of sound in all its variations and to enhance aural experience in built environment-
within and without.
MODULE 1 (Introduction to Sound and Room Acoustics)
1) Introduction to Sound: Origin and nature of sound, its characteristics and measurement– Amplitude, frequency, period, wavelength, velocity of
sound, sound pressure, sound intensity, decibel scale, sound and distance – inverse square law. human hearing, auditory range for humans
(Frequency and Intensity – threshold of audibility and pain), pitch (association with frequency), tone, loudness (association with amplitude and
intensity), Phon.
2) Room Acoustics: Reflection - Nature of reflection from plane, convex and concave surfaces, diffraction, Absorption, Echoes, focusing of sound,
dead spots, flutter echo. Room resonances, Reverberation - reverberation time (RT) calculation using Sabine’s and Eyring’s formulae. Effect of RT
on speech and music.
MODULE 2 (Acoustical Tools, Measurements and Materials)
3) Acoustical Tools and Measurements: Use of SLM (Sound Level Meter), AI (Articulation Index), STI (Speech-Transmission Index), Speech
Intelligibility. Sound Attenuation. Absorption coefficients of acoustical materials, NRC value, NC Curves for various spaces.
4) Acoustical Materials: Porous materials, panel absorbers, membrane absorbers, acoustical plasters, diffusers, cavity or Helmholtz resonators.
Role of functional absorbers, Adjustable acoustics and variable sound absorbers. Acoustical correction and retrofits to existing spaces.

3. 18 ARC 7.3 BS IV
MODULE 3 (Acoustical Design)
5) Acoustical Design of Auditoriums - Multipurpose Halls: History of Greek, Roman theatres. Use of IS code 2526 - 1963 for design and
detailing of Auditoriums - Cinema Halls - Multipurpose Halls - Halls for speech and music.
6) Acoustical Design and Detailing of Other Spaces – Open air theatres, Halls for Indoor Sports, home theatres, recording studios, open plan
offices, etc. Need and use of sound reinforcement systems, sound masking systems and speech privacy.
MODULE 4 (Noise reduction and Control)
7) Introduction to environmental noise control: Noise, its sources and its classification - outdoor and indoor, airborne and structure borne, impact
noise, noise from ventilation system, community and industrial noise. Noise transmission, Mass law and transmission loss. Maximum
acceptable noise levels. Design Principles – reduction at source, reduction near source, etc.
8) Constructional measures of noise control and sound insulation -Enclosures, Barriers, Sound insulation (AC Ducts and plants), Vibration
isolation – control of mechanical noise, floor, wall, ceiling treatment. Sound Isolation. Construction details of composite walls, double walls,
floating floors, wood-joist floors, plenum barriers, sound locks, etc. STC (Sound Transmission Class) ratings.
MODULE 5 (Noise reduction and Control-II)
9) Industrial noise: Sources of industrial noise - impact, friction, reciprocation, air turbulence and other noise. Methods of reduction by
enclosures and barriers.
10) Introduction to Urban Soundscape – Introduction to Urban noise, Noise sources - Air traffic, Rail traffic, Road traffic, Seashore and inland.
Traffic planning against outdoor noise. Noise reduction and control by Site planning, Town planning and Regional Planning consideration. Role
of Architects / Urban Planners in shaping the urban soundscape. Sustainable design strategies in building acoustics.

4. 18 ARC 7.3 BS IV
TYPES OF NOISE
The types of noise are
● Continuous noise- it’s noise that is produced
continuously, for example, by machinery that keeps
running without interruption. This could come from
factory equipment, engine noise, or heating and
ventilation systems.
● Intermittent noise - Intermittent noise is a noise
level that increases and decreases rapidly. This might
be caused by a train passing by, factory equipment
that operates in cycles, or aircraft flying above your
house.

5. 18 ARC 7.3 BS IV
● Impulsive noise - Impulsive noise is most commonly
associated with the construction and demolition industry.
These sudden bursts of noise can startle you by their fast
and surprising nature. Impulsive noises are commonly
created by explosions or construction equipment, such as
pile drivers
● Low frequency noise - Low-frequency noise makes up
part of the fabric of our daily soundscape. Whether it’s
the low background hum of a nearby power station or the
roaring of large diesel engines, we’re exposed to low-
frequency noise constantly. It also happens to be the
hardest type of noise to reduce at source, so it can easily
spread for miles around.

6. 18 ARC 7.3 BS IV
INDUSTRIAL NOISE
Industrial Noise is the sound created in the
factories and plants - it affects people who work
within and live around the industrial buildings.
Depending upon the frequency, amplitude and
range of Industrial noise - it may cause slight
annoyance to severe long term health hazards.
The sources of Industrial Noise are
● Impact
● Friction
● Rotation and reciprocation
● Air Turbulence
● Noises with pure tone components

7. 18 ARC 7.3 BS IV
IMPACT NOISE
FRICTION NOISE
● Noise caused by impact is most intense and widespread of all industrial noise.
● Connected with the resonant response of the structural members.
● Sources of these noises are forging, chipping, riveting pressing etc
● Impact noise - usually intermittent and impulsive in character, but may sometimes be continuous too
● Noise produced due to friction for processes like sawing, grinding and sanding.
● Occurs at the cutting edge of Lathes
● Spectrum of friction noise dominates in the high frequency spectrum
● Very unpleasant in character.

8. 18 ARC 7.3 BS IV
RECIPROCATING NOISE
AIR TURBULENCE NOISE
● Rotating or reciprocating machines generate noise due to unbalanced forces and pressure fluctuations
in the fluids inside the machines.
● Moving surfaces can radiate noise directly or pressure fluctuations are transmitted to the outer casings
of the machine from where they are radiated as noise.
● Noise generated by rapid variation in air pressure caused by turbulence from high velocity air,
steam or gases.
● Exhaust noise from pneumatic tools or air jets.
● Noise is intense and broad based in character, frequency criteria depends on the size of the jet.
● Intensity increases with velocity of the air stream.
NOISES WITH PURE TONE COMPONENTS
● Whining noise from turbines
● Humming noise from transformers

9. 18 ARC 7.3 BS IV
METHODS OF REDUCING NOISE
Noise Control by location
Noise reduction by Layout
Noise reduction at source
● Selection of machinery
● Reducing noise from potential sources
● Reducing transmission of mechanical vibrations (material and position of isolators)
● Flexibility of foundation
Noise reduction by Enclosures or Barriers
● Enclosures
● Barriers
Acoustical absorption devices
● Acoustical treatment of ceiling and sidewalls
● Functional sound absorbers

10. 18 ARC 7.3 BS IV
MEASURES FOR NOISE REDUCTION
Corrective measures to control Industrial noise may be any of the
following depending on the functions
● Designing the building with sound absorbent materials installed
at appropriate locations
● Segregating the machinery and people to minimise exposure of
personnel to loud machine noise
● Replacing old noisy machinery with new quiet models
● Regular maintenance of machinery to ensure minimal wear and
tear
● Create acoustical enclosures to either minimise the noise at
source or break the path of sound transmission
● Supplying personnel with PPE and ear muffles
● Explore options of innovative solutions like acoustic louvers.

11. 18 ARC 7.3 BS IV
INTRODUCTION TO URBAN SOUNDSCAPE (totality of noise in urban setting)
“Soundscape” refers to
the natural acoustic environment (animals and sounds from trees, water, weather, etc.) and
sounds created by humans (musical compositions, human activities, sounds of mechanical origin, etc.)
But noise is more than just a fact of urban life — it can actually affect human well-being.
Definition of soundscape - acoustic environment as perceived or experienced and/or understood by people, in
context
The complex urban soundscape is shaped by a combination of environmental noise from transit systems, road
traffic, construction, industry, the built environment, population density and other sources.
These sources are additive to any other sources of noise that individuals may be exposed to, the most
important of which has historically been the workplace. Certain occupations (e.g., manufacturing, construction,
etc.) present well documented risk of excessive noise exposure

12. 18 ARC 7.3 BS IV
PLANNING AND DESIGN AGAINST OUTDOOR NOISE
Planning against noise -
1. integral part of town and country planning regulations ranging from regional proposal to detailed
zoning, 3D layouts and road design within built up areas.
2. Noise generated by
● traffic (rail, road and air traffic)
● Zones and buildings ( industry, commercial, office and public buildings ) and
● Public gathering and social activities
3. Residential areas to be set back from airports, state and national highways, main railway lines
and factories.
4. Two aspects of design - creating buffer zones and green belts to keep buildings away from busy
highways etc. Secondly principle of shading and screening - interposing a less vulnerable building to screen a
more vulnerable building by providing a solid barrier.

13. 18 ARC 7.3 BS IV
Air traffic noise
2 sources of aircraft noise - flyover noise and ground noise
Flyover noise- noise under flight paths
Ground noise - Noise emitted during ground operations
● New development should not be carried out in the airport vicinity due to the sound levels which can
cause serious health issues if exposed for prolonged time.In case development in those areas become
necessary - adequate sound insulation shall be provided.
● Noise exposure in the vicinity of the airport combines many factors into a single number evaluation . A
commonly used criterion is Noise Exposure Forecast (NEF). NEF develops noise contours in the vicinity
of the airport - NEF 40 and above are not acceptable while NEF 25 are acceptable.
● No residential development be allowed beyond NEF 35 level.
● Buildings in the vicinity of the airport to be adequately sealed to minimise and erase the the airport
noise - which is possible for office buildings with central AC but will not work for residential buildings.

14. 18 ARC 7.3 BS IV
Rail traffic noise
● Noise builds up during day and night along with vibration.
● Residential and public buildings to be avoided abutting the railway lines. Industrial and Commercial
buildings are favoured to abut the railway lines.
● Underground railway lines cause noise and vibrations which cause both air borne and structure borne
noise.
Road traffic noise
● Avoid shortcut of heavy traffics through residential layouts.
● Trees with heavy foliage planted on both sides of carriageways helps to muffle the traffic noise if it
extends for a considerable distance.
● External noise to be limited to 60dBA for residential buildings with openable windows.
● Honking strictly prohibited near sensitive buildings like Hospitals.
● Barriers to be provided to shield sites from noise.

15. 18 ARC 7.3 BS IV
Noise reduction and control by Site planning, Town planning and Regional Planning consideration
● Zoning of different functional spaces such that residential buildings are zoned away from noisy
buildings. Clear segregation of Industrial zones away from and residential zones.
● Thoughtful road planning to connect different functional spaces without compromising on the noise
levels.
● Location of screening buildings (commercial buildings which are centrally air conditioned etc) between
roads and residential buildings.
● the screening buildings themselves can become sources of noise (as in the case of factories) or can be
unattractive in appearance.
● Urban planning schemes involve considerations that range from road design, to land-use planning and
to the location and architecture of buildings.
● Their configuration and cost are heavily influenced by local conditions.

16. 18 ARC 7.3 BS IV
Residential buildings
Sources of noise nuisance - Outdoor noise & Indoor noise
Recommendations
● Site planning - sited away from noisy sources, no thoroughfare through the residential areas,softscape
around residential areas, minimising hardscape
● Internal planning - Non critical and ancillary functions towards the noisy sources and habitable spaces
in the quieter zones, Windows and doors located away from noisy sources, Layout plans with suitable
acoustical partitions or buffer spaces between private and semi public spaces.
● Sound insulation - reduction of air borne noise, suppression of noise at the source,reduction of air borne
noise transmitted through structure, reduction of structure borne noise, reduction of impact noise

17. 18 ARC 7.3 BS IV
Educational buildings
Sources of noise nuisance - Outdoor noise & Indoor noise
Recommendations
● Site planning - sited away from noisy sources, planning for noisy activities in the school premises to be
sited away from spaces requiring quiet environment.
● Internal planning - Grouping, windows and ventilators, doors, acoustic sliding partitions, open planning
and circulation areas, furniture
● Noise reduction within rooms - suitable reverberation times are required based on the functional
requirement (shorter reverberation times are desirable whenever possible). Attention to be specially
given while designing for hearing impaired and visually impaired persons to ensure adequate
reverberation time.
● Sound insulation - reduction of air borne noise and impact noise (minimum sound reduction between
different rooms is 45dB )

18. 18 ARC 7.3 BS IV
Hospital buildings
Sources of noise nuisance - Outdoor noise & Indoor noise (noise consequent upon hospital routines, from PA
systems, telephones etc & noise from fixed or mobile equipments and services)
Recommendations
● Site planning - sited away from noisy sources
● Detailed planning - arranging of spaces based on functions and numerous other factors.
● Reduction of noise at source - use of resilient materials, other measures
● Reduction of noise by structural means - Insulation, Absorption

19. 18 ARC 7.3 BS IV
Office buildings
Sources of noise nuisance - Indoor noise from various machines and equipments, conversations, footsteps
etc
Recommendations
● Site planning
● Detailed planning - noise reduction within rooms (reverberation time should not exceed 1sec @500 Hz),
large general offices , lightweight construction, open plan offices, office equipment rooms, banking
halls, public offices and waiting spaces, canteen , circulation space
● Requirement of sound insulation
Hotel and Hostel buildings
Sources of noise nuisance - Outdoor noise & Indoor noise
Recommendations
● Site planning -
● Internal planning -

20. 18 ARC 7.3 BS IV
Laboratories and Test houses
Sources of noise nuisance - Outdoor noise & Indoor noise
Recommendations
● Site planning
● Internal planning
Miscellaneous buildings
● Law courts & Council Chambers
● Libraries, Museums & Art Galleries
● Auditoria & Theatres
Noise from building services

21. 18 ARC 7.3 BS IV
https://www.cirrusresearch.co.uk/blog/2020/04/4-different-types-noise/
NBC 2016-Volume II - Part 8, Section 4 - Acoustics, Sound Insulation and Noise Control
https://awv.com/blog/industrial-noise-pollution/
https://rashidfaridi.com/2013/03/19/noise-pollution-sources-and-types/
https://www.environmentalpollution.in/noise-pollution/reduce/how-to-reduce-traffic-noise-noise-pollution/5996
https://www.deeproot.com/blog/blog-entries/urban-soundscapes-creating-quiet-spaces-in-a-roaring-city/
https://acoustics.org/tag/urban-soundscapes/
https://ehjournal.biomedcentral.com/articles/10.1186/s12940-015-0006-y