Reducing noise pollution with clay brick

This year, South Africans spent their winter days at home with their children, dogs and working spouses. One of the key productivity killers, has been noise!

Noise is not only irritating, it can contributes to reduced physical and mental performance.  In an acoustically comfortable environment, we hear others more easily, focus better and feel calmer.

The density of  ceramic clay brick provides an inherent resistance to the passage of airborne sound.  Brick buildings reduce both high and low-frequency noise from outside. Masonry also isolates and protects against impact sounds on walls and floors inside the building.

Understanding sound transmission

In their research report "Measurements of Sound Transmission Loss in Masonry" William Siekman of Riverbank Acoustical Laboratories tested 15 clay brick wall types including face brick, single and double leaf walls, as well as walls with and without cavities and/or insulation.

They found that the average double-leaf plastered clay brick wall cuts over 50% of the noise from outside.  Ambient noise of around 65db (moderate to loud) is reduced to less than 20db which is barely audible.

A double skin clay brick wall is therefore defined as a superior insulator even without insulation. Because the brick has mass, it has the ability to inhibit sound penetration.

Reverberation

Another factor that influences how we perceive sound and the experience of acoustic comfort is reverberation.

Reverberation is time taken for a sound to "fade away". If the delay is greater than 0.6 seconds, people find it hard to distinguish between consonants. Factors that increase reverberation, sound reflection and echoing are:

• smooth, glossy walling materials (especially glass windows and doors)
• large, double volume rooms
• fewer objects in the room to break up the sound.

Textured rustic and face brick products are superior performers when it comes to reducing sound reflection and reverberation.

In general, masonry – whether it is clay brick, cement brick, concrete block or stone - provides superior sound control compared “poured concrete”.  Often the reinforcing steel required for cement structures “rings” with vibration throughout a large multi-story building.

Many buildings have to be retrofitted with sound insulation and acoustic panels at a huge cost. By using the right walling materials during construction,  effective acoustics are “built-in” to living, working and learning spaces.