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Noise control

Noise control [pdf 768 KB]

Noise can interfere with sleep, rest and conversation and cause fatigue, irritability, headaches and stress. Surveys show that noise is an important environmental concern for most Australians. We all need to contain and reduce noise and protect ourselves from sources of noise in order to enjoy a healthy life. Thoughtful design and practice can reduce the impact of noise on our lives and improve the quality of our living environment.

Neighbourhood noise

Common sources of neighbourhood noise include:

  • road, rail and aircraft traffic
  • air conditioners, evaporative coolers and refrigeration units
  • pool pumps
  • TVs and sound systems
  • burglar and car alarms
  • household appliances
  • dogs and other animals
  • industrial premises and backyard workshops
  • music from houses, commercial premises and concerts
  • road and building maintenance and construction.

Noise is measured by sound pressure level which is expressed as a power ratio and calibrated in decibels (dB). The ear has a large dynamic range in audio perception with the ratio of the quietest to the most immediately dangerous sound level (capable of causing permanent damage to the ear) being in the order of 1:1 trillion.

Some typical values are given in the following table. Note that it is not a linear scale — going from 50dB to 100dB is not twice as loud but 16 times as loud and from 60dB to 30dB is not half as loud but one eighth as loud.

Regular exposure for more than one minute to 110dB risks permanent hearing loss, and prolonged exposure to any noise at or above 85dB can cause gradual hearing loss (NIDCD 2012).

Communities usually agree about what noise volumes are acceptable and what are not. The intensity of sound can be measured objectively in decibels, but our perception of what constitutes noise is affected by subjective factors. These include the type of noise (one person’s music might be another person’s noise), our mood, the time of day, background noise levels and our expectations. Sudden noises such as a motorbike exhaust or screeching brakes can be more disturbing than steady or expected noises. Frequency of noise may also have different impacts.

Sound levels and their perception

Sound level (dB)

Approximate loudness relative to ordinary conversation

Perception example

Sources: NIDCD 2011 and Trace/University of Wisconsin

0

Don’t hear anything

Threshold of hearing

10

1/32 as loud

Very faint normal breathing

20

1/16 as loud

Quiet room

30

1/8 as loud

Quiet conversation/quiet office interior

40

1/4 as loud

Moderate quiet office/quiet rural area

50

1/2 as loud

Quiet suburban area/dishwasher in next room

60

Ordinary conversation

Average office/ordinary conversation

70

Twice as loud

Loud busy street/vacuum cleaner at 3m

80

4 times as loud

Noisy office/passing car at 3m

90

8 times as loud

Very loud heavy traffic/passing bus or truck at 3m

100

16 times as loud

Loud car horn/passing subway train at 3m

110

32 times as loud

Pop group/night club with band playing

120

64 times as loud

Extreme; jet take-off at 100m

Options to reduce noise

Recognising these subjective factors helps us determine when others are creating noise unfairly and how to respond. If neighbourhood noise is a genuine problem for you, or you believe that you might generate noise that could affect others there are some actions you can take:

  • Choose a quiet neighbourhood.
  • Reduce the noise by talking it over with whoever is causing the problem, or by lodging a complaint.
  • Block the noise with barriers, sound absorbent materials and appropriate home design.
  • Minimise your own contribution to neighbourhood noise.
  • Carry out noisy activities during the day.
  • Inform your neighbours whenever you need to generate noise, such as a party at home.
  • Design your home to minimise noise transfer to your neighbours.
  • Select a home that is well designed to limit noise transfer.

Traffic noise

For most Australians road noise is the most important neighbourhood noise issue as it affects a high proportion of the population, and the problem is growing as traffic levels increase. A 2003 study indicated that 20% of Sydney’s population were exposed to levels of road traffic noise that were well above those recommended by the World Health Organization for reducing annoyance and sleep disturbance. Many people complain that traffic noise has the greatest direct impact (see Transport).

Minimise the impact of traffic noise on your home — and your contribution to the problem:

  • Cycle or walk, rather than drive.
  • Buy a quiet car, and drive it less.
  • Drive slowly and calmly and maintain your car.
  • Shop locally and buy locally made products to reduce freight travel.
  • Report noisy vehicles.

Take measures in the design of your home such as using suitable window glazing, managing air leakage, and designing shared walls and floors to limit noise transfer.

Queensland identifies designated transport corridors and New South Wales has a road noise policy. Check with your planning authority to see if your property is contained in a designated transport noise corridor (rail or road) or is otherwise recognised as being subject to higher than average transport noise levels. If so, measures need to be taken to ensure that your home includes appropriate design responses to the noise corridor.

Work with your neighbourhood, local council, community organisations and government to create more livable communities with reduced traffic noise. Central to this is the creation of urban villages based on public transport, walking, cycling, traffic calming and other traffic reduction initiatives (see Transport).

Noise in buildings

Non-traffic-related noise complaints are rising, particularly in medium and high density housing areas. Many new medium and high density developments are unnecessarily noisy, and the sound insulation requirements for multi-unit housing and apartment buildings are not particularly high.

It can be very difficult or expensive to do anything about a noise nuisance after a house is built or purchased. Consider potential noise problems before you buy, build or renovate.

Ask for design specifications for noise levels before buying a multi-residential unit and ask your solicitor to link them to your contract as a performance measure. This will give you more options if you discover a problem after moving in.

Part 3.8.6 of the Building Code of Australia (BCA), Volume Two, contains sound insulation requirements and technical solutions for separating walls and floors within and between dwellings.

The following design sound levels are recommended for an inner suburban house.

Recommended design levels

Activity

Satisfactory (dB)

Maximum (dB)

Source: Standards Australia 2000

Recreation areas

35

40

Bedrooms

30

35

Work areas

35

40

Types of noise

There are two types of building noise to consider: airborne and impact.

Airborne noise

Airborne noise comes from common sound sources such as voices, TVs and radios. The noise performance of a building structure is called the Sound Transmission Class (STC). The higher the STC the better the structure is at isolating airborne noise. An STC rating of 45 means that the sound passing through the building is reduced by 45dB.

Rooms with a lot of hard surfaces can be very noisy as they readily reflect sound. Soft furnishings, drapes and rugs can make a significant improvement. Hard floor surfaces can create impact noise.

A change of 3 STC (or dB) in the sound level means a doubling or halving of the sound energy. As the human ear does not perceive sound in a linear way, a 3dB change is barely perceptible. The following table shows the subjective perception of sound energy. Roughly speaking, a 10dB reduction makes a sound appear to be half as loud. The next table outlines what this means in practice for a building.

Subjective perception of sound energy reductions

Reduction in dB

Percentage

Reduction in sound energy subjective perception

3

50

Barely perceptible

4−5

70

Significant

6

75

Sound appears to be reduced by about one quarter

7−9

87

Major reduction

10

90

Sound appears to be less than half original

Effect of sound transmission classes on speech perception

Sound Transmission Class

Effect on speech perception

25

Normal speech can be heard easily

30

Loud speech can be heard easily

35

Loud speech can be heard but not understood

42

Loud speech heard as murmur

45

Must strain to hear loud speech

48

Loud speech can be barely heard

53

Loud speech cannot be heard

Impact noise

Structure-borne noise, also called impact noise, is produced when part of the building fabric is directly or indirectly affected. Energy passes through the structure and creates noise in nearby rooms. Examples are heavy footsteps (particularly on bare timber or tile floors), banging doors, scraping furniture, vibrations from loud music and plumbing noises. The Impact Insulation Class (IIC) is used to rate the impact noise insulation of floors.

Noise and good design

Site planning

Consider noise sources such as shops, hotels, and garbage and recycling collection when siting, buying or renovating your home and locating windows.

There are proprietary fencing or ‘sound wall’ options designed to provide noise abatement (reportedly up to 43dB). These solutions can result in large, potentially unattractive areas of vertical hard surfaces but can be enhanced with the addition of decorative elements that also contribute to sound attenuation. Large masonry based sound walls and fences are generally appropriate on the boundary of domestic dwellings with more public areas rather than between dwellings and suburban backyards.

A screen wall is built between a noise source and a house.

Place a screen between dwelling and noise source.

Dense vegetation can significantly reduce noise transmission in a number of ways — a soft earth surface reduces the intensity of low frequency sound by absorbing its energy, and leaves and stems scatter high frequency sound waves.

  • Place walls, fences, trees and screening vegetation between the noise source and your home.
  • Place driveways and garages away from bedrooms and living rooms.

Building layout and design

The best protection against noise is to avoid making it in the first place, or by ensuring that noise sources are not too close. Noise levels vary through different times of the day, so it is worthwhile to try and take account of when noise is, or might be, generated.

Sound ‘leaks’ through gaps surprisingly easily, so your building’s construction material, design and layout can make a big difference.

  • Locate quiet rooms as far away from noise sources as possible, without compromising passive solar design principles.
  • Install windows away from noise sources if possible and select sound absorbing types.
  • Locate noisy areas together and away from quiet areas.
  • Avoid putting laundries, bathrooms or living rooms next to, above or below bedrooms without adequate sound insulation. Consider mounting noisy appliances on sound absorbing pads.
  • Accommodate teenagers by providing extra soundproofing for their rooms and locate them away from adult living and sleeping areas, and neighbours.

A cross-section of a two-storey house showing a variety of noise sources associated with various room usages.

Consider noise levels when planning the use of each room.

Noise is a particular problem within medium and high-density housing, and special care in design is needed to avoid problems. If people are unable to open windows to keep cool in summer they may need to install mechanical cooling.

  • Minimise the need for noisy mechanical cooling.
  • Use acoustic ‘fins’ (solid non-loadbearing walls) between balconies.
  • Build units around quiet courtyards and face them away from roads.
  • Keep pedestrian and vehicle thoroughfares away from bedrooms and living rooms.
  • Avoid placing windows and doors of neighbouring units opposite or adjacent to one another.

A passive home is designed to encourage airflows that distribute heat or ‘coolth’ through the building. This tends to enhance sound transmission between the building’s internal spaces, so careful consideration of the sound transmission and reflection qualities of internal surfaces is especially important.

Construction

Thermal mass is a poor thermal insulator but can provide good acoustic insulation between rooms and apartments, or from outdoor noise, although it may also reflect sound and transmit impact noise (see Thermal mass).

The BCA specifies the minimum STC wall and floor requirements between adjoining dwellings, but uses a sound reduction index (Rw) which is directly equivalent to STC. An increase of one Rw unit approximately equals a reduction of one decibel in noise level. An increase of 10 Rw units approximately halves the sound transmitted (CSR 2011).

The BCA specifies the minimum required Rw (airborne) + Ctr (impact) sound values for separating wall construction in new single dwellings (Class 1 buildings). For further information please refer to Part 3.8.6 of Volume Two of the BCA. Exceeding the minimum specifications is highly recommended, particularly given the trend towards higher density living. The BCA does not specify IIC, but certain construction types are ‘deemed to comply’.

Rw levels in the BCA only consider individual building elements as measured in a laboratory. Sound transmission properties of the structure as a whole or on-site construction practices are not taken into account. These can reduce the effective value by up to 5 Rw due to flanking sound transmission paths, for example through structural components.

Good design detail and construction practice is critical to the performance of both heavy and light construction.

  • Pay attention to building components such as floor and ceiling plates and to the installation of services such as plumbing and power outlets; insulate them acoustically if necessary to ensure the desired performance is achieved.
  • Avoid locating plumbing and waste pipes close to quiet rooms or ensure that they are adequately soundproofed — a range of sound insulation products exists for plumbing and waste pipes in walls and floors.

PVC pipe is wrapped in sound insulation, passing through a batt-insulated timber stud and plasterboard wall.

Sound-insulated plumbing in a stud wall.

A PVC pipe wrapped in sound insulation passes through a batt-insulated acoustic mount floor.

Sound-insulated plumbing in a floor.

  • Provide extra sound insulation for noisy rooms such as laundries. Use acoustic mounts or pads for clothes washers and dryers.
  • Use built-in robes as sound buffers between bedrooms.
  • Use solid core doors which are more effective sound insulators than hollow core.
  • Use door closers or foam/plastic strips on door frames to stop doors banging.
  • Reduce sound reflection transmission through gaps with draught sealing strips.
BCA Rw requirements for walls between adjoining dwellings

Structure

Minimum reduction index (Rw)

*These walls must also have a satisfactory level of impact insulation as outlined in the code

Source: ABCB 2011

Floors above dwellings

50

Walls between a bathroom, laundry or kitchen and a habitable room in adjoining dwelling*

50

Other walls

45

For the BCA minimum requirements for Rw (airborne) + Ctr (impact) sound values for separating wall construction in new single dwellings (Class 1 building) please refer to Part 3.8.6 of Volume Two of the BCA. Although the BCA specifies no sound insulation requirements within dwellings it is important to consider sound transmission in homes now that multiple TVs, sound systems and bathrooms are common.

The Rw ratings of some typical wall and floor construction methods are outlined here. Heavy dense materials, such as concrete, are generally better for sound insulation but a range of lightweight solutions are also available.

Walls

Rw32 — Using 10mm plasterboard on 100 x 50mm timber studs at 450mm centres provides very little sound insulation and is not recommended for occupied rooms.

Rw32

Rw42 — 100mm low density AAC block with 10mm adhered plasterboard both sides.

Rw42

Rw45 — 90mm calcium silicate brick with adhered 10mm plasterboard both sides. This complies with the BCA minimum for adjoining dwellings.

Rw45

Rw50 concrete — 90mm solid concrete block with adhered 10mm plasterboard both sides.

Rw50 concrete

Rw50 timber frame — 16mm fire protective plasterboard on staggered timber 70 x 45mm studs at 600mm centres both sides with 120 x 35mm timber plates and 50mm glass fibre batts.

Rw50 timber frame

High density insulation, multiple layers of plasterboard and foam backed plasterboard also help control noise transmission — internal stud walls can be filled with high density insulation which provides acoustic insulation and also increases thermal resistance. This is particularly useful between inhabited and uninhabited spaces like laundries.

Pay special attention to details that might affect the integrity of sound insulation such as power points and plasterboard joints. Offset power outlets and locate them in different sections of the wall cavity. Use sealed power outlets to prevent air leakage (see Sealing your home).

Power outlets on opposite sides of a stud wall are offset to minimise noise leakage.

Offset power outlets to minimise noise leakage.

Ensure the joints overlap and offset joints on opposite sides of the wall when using double layers of plasterboard.

Diagram of stud wall shows offset joints between two layers of plasterboard sheets.

Offset plasterboard joints when layering the boards.

Internal floors

Rw35 — Bare 20mm floorboards on 200 x 50mm joists at 450mm centres, with one layer of 13mm plasterboard, provides very little sound or impact insulation and is not recommended.

Rw35

Rw48 — 150mm concrete slab (365kg/m2) with 10mm of plaster.

Rw48

Rw50, IIC 50 — Bare 20mm floorboards on 200 x 50mm joists at 450mm centres, with two layers of 16mm fire protective plasterboard on furring channels and resilient mounts, and 100mm batts. Using carpet and underlay will increase the IIC to 70.

Rw50

Dense materials will, however, readily transmit impact noise. Composite construction using combinations of light and heavy mass materials are best to reduce noise transmission.

Two wall constructions.
1. Heavy material (concrete, brick) sandwiches light material (polystyrene sheet, batts).
2. Studs, lightweight batts and plasterboard sandwich heavy material (conrete, brick).

Composite constructions for reducing noise transmission.

Precast concrete — sound transmission ratings for some typical precast concrete flooring and walling systems are shown below.

Sound transmission class and mass for slabs and walls

Solid slabs or walls

Slab/wall type

Mass kg/m2

STC

50mm

115

43

70mm

161

47

100mm

230

50

150mm

345

52

200mm

460

58

Hollowcore slabs

Slab/wall type

Mass kg/m2

STC

150mm

220

48

200mm

278

50

250mm

312

50

Screens — Provide screen walls to shield noise and use acoustic materials to reduce reflection of airborne noise.

  • Avoid hard floor surfaces that are above ceilings without good sound insulation. Use cork, carpet or impact absorbing finishes instead of bare timber or tiles.
  • Use low density coverings such as carpet which will have little effect on STC but will greatly reduce both impact noise (increasing the IIC by about 20 points) and internal sound reflection.
  • Use proprietary noise reduction underlay to increase both STC and IIC ratings of floors. They are ideal for reducing sound transmission on existing floors within a home.
  • Install bulk insulation under floors to damp down noise and reduce noise transfer.
  • Encourage people to remove their shoes in the home.

A car is parked next to a house. A screen wall extending from the front side wall of the house screens the car space from the outdoor area in front of the house.

A screen wall shields outdoor living space from vehicle noise.

Noise from outside a building is reflected around a balcony space.

Use acoustic material to reduce reflection of airborne noise.

Glass and noise

A 3mm single glazed window has a very low STC, and windows can let in a lot of noise, open or closed. The potential sound reduction from a highly insulating wall can be substantially reduced by poor window design.

Double glazing and laminated glass are both effective at reducing noise provided the windows are closed and the frames are well sealed.

The table below shows the percentage noise reduction compared to 3mm glass. Note that these percentage reductions are not the same as STC values.

Noise reduction for glazing compared to 3mm glass

Single glazing

Glazing type

Voice noise reduction (percentage)

Traffic noise reduction (percentage)

Source: Pilkingtons

6.38mm laminated

13

24

10mm glass

24

38

10.38mm laminated

29

43

Double glazing

Source: Pilkingtons

Glazing type

Voice noise reduction (percentage)

Traffic noise reduction (percentage)

4mm/12mm space /4mm

19

 

10mm/12mm space/ 6.38mm laminated

 

46

10mm/12mm space/6mm

34

 

6mm/100mm space/4mm

 

57

6.38mm laminated/ 8mm space/4mm

46

 

NOTE: Thicker glass generally does not improve thermal insulation. For a combination of sound and thermal insulation use double glazing. Bear in mind that the acoustic insulation of any window is severely compromised when it is open (see Glazing).

To maintain effective ventilation with doors and windows closed, consider installing acoustic wall vents which are designed to provide ventilation while minimising noise transmission (see Sealing your home).

Outdoor noise sources

  • Site noisy areas like swimming pools and outdoor living areas away from neighbours’ windows.
  • Avoid using hard exterior surfaces such as concrete paving, which reflects sound rather than absorbs it. Softer surfaces are more desirable, particularly in higher density housing, as they absorb sound. Permeable surfaces also reduce stormwater runoff (see Stormwater).
  • Make sure outdoor noise sources (air conditioning units, pool pumps) are not going to be a nuisance for neighbours. If pumps can’t be placed far enough away, build a noise reduction enclosure, but make sure it does not undermine the efficiency of the equipment by blocking air flow.

There are laws governing noisy air conditioners and pumps that may annoy neighbours. Buy the quietest air conditioner suited to your needs, and install it as far as possible from your neighbour or in a well-shielded location.

Most air conditioners in Australia have a label that specifies the amount of noise they make. The smaller the dBA number on the label, the quieter the air conditioner. Get specialist advice from the supplier or installer. Evaporative coolers on roofs can be a major noise problem: choose a quiet model and locate it on a roof slope away from neighbours.

An air conditioning unit is placed on the side of one house, directly facing the neighbouring house.

Unsuitable location for an air conditioner.

An air conditioning unit is placed on the rear wall of a house so that it does not face the neighbouring house. A small screen wall next to the AC unit also screens it from the neighbouring house.

Air conditioning unit faces away from neighbours and is screened by a wall.

Erect appropriate sound barriers and plant vegetation to reduce or modify the impact of noise both from and to your home.

References and additional reading

Contact your state, territory or local government for further information on noise control in residential areas: www.gov.au

Anderson, L, Mulligan, B and Goodman, L. 1984. Effects of vegetation on human response to sound. Journal of arboriculture 10(2).

CSR. 2011. The red book: fire and acoustic design including green building systems. North Ryde, NSW. www.gyprock.com.au

Ecotect community WIKI. 2012. Sound: barriers. [additional reading now found on http://wiki.naturalfrequency.com]

National Institute on Deafness and Other Communication Disorders. 2012. Bookmark, NIDCD, National Institutes of Health, Bethesda, MD. www.nidcd.nih.gov

NSW Department of Environment, Climate Change and Water. 2011. NSW road noise policy. www.environment.nsw.gov.au/noise/traffic.htm

Queensland Department of Housing and Public Works. 2012. Transport noise corridors. [additional reading now found on www.acoustics.asn.au]

Authors

Principal author: Geoff Milne

Contributing authors: Kendall Banfield, Chris Reardon

Updated by Paul Downton, 2013