Lowering the amount of noise in urban areas

Urban noise has become a serious national problem affecting most Australians on a daily basis. Although many factors conspire to produce urban noise, the cause is no mystery - high-density living.

Rex Broadbent, Manager of the CSIRO Acoustics Laboratory, says, "Back at the start of the baby boom, people were living in houses situated on quarter-acre blocks with their own garden and plenty of space between them. Now, increased population density means there can be 12 families living in the same area, very close to each other."

The problem is compounded by the advent of lightweight building materials (in place of the traditional brick construction) and all the trappings of modern living - household machinery, power tools, air conditioners, amplified entertainment systems with bass sub-woofers, and motor vehicles.

Traffic noise alone has been found to affect 50 per cent of the Australian population, with 10 per cent experiencing severe vehicle noise.

Reports have also found that unbearable aircraft noise and neighbourhood noise affect many suburbs on a daily basis, resulting in a large number of noise complaints and legal disputes.

Not only is noise frustrating and annoying, it can have major adverse lifestyle effects. It can interfere with sleep, health, happiness, employment and property values. It can also cause stress, driver fatigue and hearing loss.

In America, noise has even been found to adversely affect learning in schools. Broadbent says, "'CSIRO was commissioned some time ago to measure the acoustics in Melbourne schools adjacent to main roads. Fortunately, we found that the schools were well designed and insulated from sound, but this type of evaluation and acoustics advice can be invaluable to customers."

How can the problem of urban noise be addressed? One major solution is to test building materials for their ability to dampen sound before they are made, says Broadbent. "Over the past five years or so, there has been a steady demand for acoustic testing services and advice relating to building materials and objects. The demand is being driven by manufacturers and regulators interested in meeting customer and building code requirements."

Acoustic testing is carried out in the Acoustics Laboratory at CSIRO Manufacturing & Infrastructure Technology. The laboratory offers three types of services:

• Acoustic testing of products and materials;
• Testing and development of new products;
• Provision of advice on acoustic-related issues.

Acoustics testing is carried out at Highett, Melbourne, usually for products/materials that are yet to be manufactured. The material or product is brought to the laboratory where it is built into the test chambers and tested for its sound-insulation capability.

This service has important ramifications for the acoustic environment of homes and buildings and ultimately the community.

The laboratory conducts the following tests:

• Airborne sound insulation of walls, floors, doors and windows;
• Impact sound insulation of floors and walls;
• Impact sound reduction of floor coverings;
• Sound absorption of materials or objects;
• Sound power level of sources;
• Airflow resistance of acoustic materials;
• Loss factor of vibration damping materials.

New products can be tested and developed by CSIRO with up-front advice on feasibility. Broadbent says, "We can often evaluate and make comments on proposed products or materials before they are even tested, and give guidance about whether the product or material would behave well acoustically. This kind of advice can shape the future of the product/material in the early stages where it is most needed and save the client unwanted costs down the line."

"Traffic noise alone has been found to affect 50 per cent of the Australian population, with 10 per cent experiencing severe vehicle noise."